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Deep Dive into Changing Database Collation

By Lowell Izaguirre,

Have you ever been in a situation where the entire database's collation needs to be changed? You may or may not know this, but the collation can be found at three different levels. At the server itself you can find a Default Server Collation. In a specific database itself, any new columns will inherit the Database Collation (unless explicitly set to something different), and finally each individual column has it's own (potentially different) collation, which can be viewed in sys.columns

Changing the database colaltion does not affect columns that already exist; they maintain their previous collation until you explicitly change it.

Here's a quick query to familiarize you with some details:

SELECT  SERVERPROPERTY('Collation')               As ServerCollation;
SELECT  DATABASEPROPERTYEX(db_name(),'Collation') AS DatabaseCollation;
SELECT  
  OBJECT_SCHEMA_NAME(object_id) As SchemaName,
  OBJECT_NAME(object_id) ObjectName,
  name As ColumnName,
  column_id,
  collation_name
from sys.columns WHERE collation_name is not null
order by SchemaName,ObjectName,column_id;

The Problem

Now suppose you inherited a database with a case sensitive collation, or a different collation, and that business requirements decide it needs to use something different instead. You've decided the database has the wrong collation, and since it's been around a while, you cannot just drop the database and create a new one. You need the data inside the database as well!

The Ramifications

Tackling that can be a huge problem, because the collations affect everything that touches the columns in the database that are using the CHAR,VARCHAR,NCHAR, and NVARCHAR data types. The columns can potentially be referenced by indexes, default values, check constraints, unque constraints, even primary keys can be directly affected, and can require a huge amount of work to modify them.

Just tackling colllation to modify one table can be daunting, but the prototype script here can help you tackle the problem with a straightforward,systematic script to build the commands you need to run. The script here only generates the commands you need, but there's an optional cursor commented out in the code as well, if you are really confident in the code it generates.

I would at least recommend running the results line by line in your test database a few times, before really committing to a cursor.

The Methodology

The idea I built here is build the scripts , in the "proper" order, to find and change the collation of any affected objects. I'm finding the tables and columns that are affected, and then digging into all the objects i could think of that use or reference the affected columns.

Additionally, the idea here is an "all or nothing" collation approach, where you intend to change the collation of all objects, and not a select number of tables to the new collation.

The Details

I decided to perform the changes in the following order:

  • STEP_000 find the columns that are not the same as the new, target collation.
  • STEP_001 find check constriants to be changed.
  • STEP_002 find default constraints to be changed.
  • STEP_003 find calculated column definitions to be changed.
  • STEP_004 find foreign key constraints to be changed

Next handle complex constraints and indexes (unique/pk/regular/includes/filtered indexes)

  • STEP_005 find primary keys to be changed.
  • STEP_006 find unique indexes to be changed.
  • STEP_007 find regular indexes(also featuring includes or filtered indexes) to be changed.

Now move to the columns themselves

  • STEP_008 actual Column Collation definitions.

Now we handle views that reference any of the object tables

  • STEP_009 refresh dependent views, procs and functions.
The core of the whole exercise is to find what might need to be changed in the first place. that is your baseline to start digging deeper to find what other objects would be affected. This query finds any columns that don't match the target collation:
    DECLARE @NewCollation VARCHAR(50)

    SET @NewCollation = 'SQL_Latin1_General_CP1_CI_AS' -- change this to the collation that you need
    --WAS 'SQL_Latin1_General_CP1_CI_AS'
    --toggling 'Latin1_General_CI_AS' 
      SELECT
        objz.object_id,
        SCHEMA_NAME(objz.schema_id) AS SchemaName,
        objz.name AS TableName,
        colz.name AS ColumnName,
    colz.collation_name,   colz.column_id FROM   sys.columns colz        INNER JOIN sys.tables objz          ON colz.object_id = objz.object_id WHERE  colz.collation_name IS NOT NULL    AND objz.is_ms_shipped = 0    AND colz.is_computed = 0    AND colz.collation_name <> @NewCollation
    

For each item that needs to be changed, we can generate both the drop and create, or simply the alter command, depending on the object. In my code, I inserted the above results into a temp table named  #MyAffectedTables. That table is used to join against sys.check_constraints, sys.default_constraints, and a host of other sys views in order to generate the commands needed to toggle collation from one type to another.

Here’s the whole script in detail, but it is attached to the end as an attachment as well.

--#################################################################################################
--Collation Changer Version 1 by Lowell  
--because of a reference to 'sys.sql_expression_dependencies', this is valid only
--For SQL2008 and above.
--Brainstorm: first map out a list of all the objects to change;
--simple constraints
--STEP_001 check constraints
--STEP_002 default constraints
--STEP_003 calculated column definitions
--STEP_004 foreign key constraints

--complex constraints and indexes (unique/pk/regular/includes/filtered indexes)
--STEP_005  primary keys 
--STEP_006  unique indexes
--STEP_007 regular indexes(also featuring includes or filtered indexes)

--columns themselves
--STEP_008 Column Collation definitions
--views that reference any of the object tables

--STEP_009 refresh dependent views, procs and functions

--#################################################################################################
--#################################################################################################
--Declare and assign our lone variable
--#################################################################################################
DECLARE @NewCollation VARCHAR(128) = 'SQL_Latin1_General_CP1_CI_AS' -- change this to the collation that you need
--WAS 'SQL_Latin1_General_CP1_CI_AS'
--toggling 'Latin1_General_CI_AS' 

--create table on the fly, add the DROP CONSTRAINTS
SELECT
  IDENTITY(INT, 1, 1) AS ID,
  0 AS ExecutionOrder, '--Suite of commands to change collation of all columns that are not currently ' + QUOTENAME(@NewCollation) AS Command
INTO
  #Results
--#################################################################################################
--Start a transaction? might cause huge bloating of the transaction log, but too bad.
--#################################################################################################  
----INSERT INTO #Results
----            (ExecutionOrder,Command)
----SELECT 1,'SET XACT_ABORT ON' UNION ALL
----SELECT 2,'BEGIN TRAN' UNION ALL
----SELECT 1000, 'COMMIT TRAN'           
SELECT
  objz.object_id,
  SCHEMA_NAME(objz.schema_id) AS SchemaName,
  objz.name AS TableName,
  colz.name AS ColumnName,
  colz.collation_name,
  colz.column_id
INTO
  #MyAffectedTables
FROM   sys.columns colz
       INNER JOIN sys.tables objz
         ON colz.object_id = objz.object_id
WHERE  colz.collation_name IS NOT NULL
   AND objz.is_ms_shipped = 0
   AND colz.is_computed = 0
   AND colz.collation_name <> @NewCollation
--AND colz.collation_name <> @NewCollation

--################################################################################################# 
--STEP_001 check constriants
--#################################################################################################
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  10 AS ExecutionOrder,
  CONVERT(VARCHAR(8000), 'ALTER TABLE ' + QUOTENAME(tabz.SchemaName) + '.' + QUOTENAME(tabz.TableName) + ' DROP CONSTRAINT ' + QUOTENAME(conz.name) + ';') AS Command
FROM   sys.check_constraints conz
       INNER JOIN #MyAffectedTables tabz
         ON conz.parent_object_id = tabz.object_id
            AND conz.parent_column_id = tabz.column_id

--add the recreation of the constraints.
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  100 AS ExecutionOrder,
  CONVERT(VARCHAR(8000), 'ALTER TABLE ' + QUOTENAME(tabz.SchemaName) + '.' + QUOTENAME(tabz.TableName) +   ' ADD CONSTRAINT ' + QUOTENAME(conz.name) + ' CHECK ' + conz.definition + ';') AS Command
FROM   sys.check_constraints conz
       INNER JOIN #MyAffectedTables tabz
         ON conz.parent_object_id = tabz.object_id
            AND conz.parent_column_id = tabz.column_id

--################################################################################################# 
--STEP_002 default constriants
--################################################################################################# 
/*--visualize the data
SELECT * 
FROM sys.default_constraints conz
  INNER JOIN #MyAffectedTables tabz
    ON  conz.parent_object_id = tabz.object_id
    AND conz.parent_column_id = tabz.column_id
*/
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  20 AS ExecutionOrder,
  CONVERT(VARCHAR(8000), 'ALTER TABLE ' + QUOTENAME(tabz.SchemaName) + '.' + QUOTENAME(tabz.TableName) +   ' DROP CONSTRAINT ' + QUOTENAME(conz.name) + ';') AS Command
FROM   sys.default_constraints conz
       INNER JOIN #MyAffectedTables tabz
         ON conz.parent_object_id = tabz.object_id
            AND conz.parent_column_id = tabz.column_id

INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  200 AS ExecutionOrder,
  CONVERT(VARCHAR(8000), 'ALTER TABLE ' + QUOTENAME(tabz.SchemaName) + '.' + QUOTENAME(tabz.TableName) +   ' ADD CONSTRAINT ' + QUOTENAME(conz.name) + ' DEFAULT ' + conz.definition + ' FOR ' + quotename(tabz.ColumnName) + ';')  AS Command
FROM   sys.default_constraints conz
       INNER JOIN #MyAffectedTables tabz
         ON conz.parent_object_id = tabz.object_id
            AND conz.parent_column_id = tabz.column_id

--################################################################################################# 
--STEP_003 calculated columns : refering internal columns to the table
--################################################################################################# 
-- need distinct in case of a calculated columns appending two or more columns together: 
-- we need the definition only once.

INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  30 AS ExecutionOrder,
  'ALTER TABLE ' + QUOTENAME(SCHEMA_NAME(objz.schema_id)) + '.' + QUOTENAME(objz.name) + ' DROP COLUMN '   + QUOTENAME(colz.name) + ';' AS Command
FROM   sys.columns colz
       LEFT OUTER JOIN sys.tables objz
         ON colz.[object_id] = objz.[object_id]
       LEFT OUTER JOIN sys.computed_columns CALC
         ON colz.[object_id] = CALC.[object_id]
            AND colz.[column_id] = CALC.[column_id]
       --only calculations referencing columns
       LEFT OUTER JOIN sys.sql_expression_dependencies depz
         ON colz.object_id = depz.referenced_id
            AND colz.column_id = depz.referencing_minor_id
       INNER JOIN #MyAffectedTables tabz
         ON depz.referenced_id = tabz.object_id
            AND depz.referenced_minor_id = tabz.column_id
 WHERE  colz.is_computed = 1

INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  300 AS ExecutionOrder,
  'ALTER TABLE ' + QUOTENAME(SCHEMA_NAME(objz.schema_id)) + '.' + QUOTENAME(objz.name) + ' ADD ' + QUOTENAME(colz.name) + 'AS ' + ISNULL(CALC.definition, '') 
  + CASE
      WHEN CALC.is_persisted = 1
      THEN ' PERSISTED'
      ELSE ''
    END + ';' AS Command
FROM   sys.columns colz
       LEFT OUTER JOIN sys.tables objz
         ON colz.[object_id] = objz.[object_id]
       LEFT OUTER JOIN sys.computed_columns CALC
         ON colz.[object_id] = CALC.[object_id]
            AND colz.[column_id] = CALC.[column_id]
       --only calculations referencing columns
       LEFT OUTER JOIN sys.sql_expression_dependencies depz
         ON colz.object_id = depz.referenced_id
            AND colz.column_id = depz.referencing_minor_id
       INNER JOIN #MyAffectedTables tabz
         ON depz.referenced_id = tabz.object_id
            AND depz.referenced_minor_id = tabz.column_id
 WHERE  colz.is_computed = 1

--################################################################################################# 
--STEP_004 foreign key constriants :child references
--################################################################################################# 
/*--visualize the data
--at least in my case, it is very rare to have a char column as the value for a FK; my FK's are all int/bigint
--I had to create a fake pair of tables to test this.
*/
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  40 AS ExecutionOrder,
  CONVERT(VARCHAR(8000), 'ALTER TABLE ' + QUOTENAME(tabz.SchemaName) + '.' + QUOTENAME(tabz.TableName) +   ' DROP CONSTRAINT ' + QUOTENAME(conz.name) + ';') AS Command
FROM   sys.foreign_keys conz
       INNER JOIN sys.foreign_key_columns colz
         ON conz.object_id = colz.constraint_object_id
       INNER JOIN #MyAffectedTables tabz
         ON conz.parent_object_id = tabz.object_id
WHERE  tabz.object_id = colz.parent_object_id
   AND tabz.column_id = colz.parent_column_id

--foreign keys, potentially, can span multiple keys;  
--'scriptlet to do all FK's for reference.
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  --FK must be added AFTER the PK/unique constraints are added back.
  850 AS ExecutionOrder,
  'ALTER TABLE ' 
  + QUOTENAME(schema_name(conz.schema_id) )
  + '.' 
  + QUOTENAME(OBJECT_NAME(conz.parent_object_id)) 
  + ' ADD CONSTRAINT ' 
  + QUOTENAME(conz.name) 
  + ' FOREIGN KEY (' 
  + ChildCollection.ChildColumns 
  + ') REFERENCES ' 
  + QUOTENAME(SCHEMA_NAME(conz.schema_id)) 
  + '.' 
  + QUOTENAME(OBJECT_NAME(conz.referenced_object_id)) 
  + ' (' + ParentCollection.ParentColumns 
  + ') ' 
  + ';' AS Command
FROM   sys.foreign_keys conz
       INNER JOIN sys.foreign_key_columns colz
         ON conz.object_id = colz.constraint_object_id
       INNER JOIN #MyAffectedTables tabz
         ON  conz.parent_object_id = tabz.object_id
         AND tabz.column_id = colz.parent_column_id
       INNER JOIN (--gets my child tables column names   

SELECT
 name,
 ChildColumns = STUFF((SELECT 
                         ',' + REFZ.name
                       FROM   sys.foreign_key_columns fkcolz
                              INNER JOIN sys.columns REFZ
                                ON fkcolz.parent_object_id = REFZ.object_id
                                   AND fkcolz.parent_column_id = REFZ.column_id
                       WHERE fkcolz.parent_object_id = conz.parent_object_id
                           AND fkcolz.constraint_object_id = conz.object_id
                         ORDER  BY
                        fkcolz.constraint_column_id
                       FOR XML PATH('')), 1, 1, '')
FROM   sys.foreign_keys conz
      INNER JOIN sys.foreign_key_columns colz
        ON conz.object_id = colz.constraint_object_id
GROUP  BY
conz.name,
conz.parent_object_id,--- without GROUP BY multiple rows are returned
 conz.object_id
    ) ChildCollection
         ON conz.name = ChildCollection.name
       INNER JOIN (--gets the parent tables column names for the FK reference
                  SELECT
                     name,
                     ParentColumns = STUFF((SELECT
                                              ',' + REFZ.name
                                            FROM   sys.foreign_key_columns fkcolz
                                                   INNER JOIN sys.columns REFZ
                                                     ON fkcolz.referenced_object_id = REFZ.object_id
                                                        AND fkcolz.referenced_column_id = REFZ.column_id
                                           WHERE  fkcolz.referenced_object_id = conz.referenced_object_id
                                              AND fkcolz.constraint_object_id = conz.object_id
                                            ORDER BY fkcolz.constraint_column_id
                                            FOR XML PATH('')), 1, 1, '')
                   FROM   sys.foreign_keys conz
                          INNER JOIN sys.foreign_key_columns colz
                            ON conz.object_id = colz.constraint_object_id
                           -- AND colz.parent_column_id 
                   GROUP  BY
                    conz.name,
                    conz.referenced_object_id,--- without GROUP BY multiple rows are returned
                    conz.object_id
                  ) ParentCollection
         ON conz.name = ParentCollection.name

--################################################################################################# 
--STEP_005, 006 and 007  primary keys,unique indexes,regular indexes
--################################################################################################# 
/*pre-quel sequel to gather the data:*/
SELECT
  CASE
    WHEN is_primary_key = 1
    THEN 'ALTER TABLE ' + QUOTENAME(SCHEMA_NAME) + '.' + QUOTENAME(OBJECT_NAME) + ' DROP CONSTRAINT ' + QUOTENAME(index_name) + ';'
    WHEN is_unique_constraint = 1
    THEN 'ALTER TABLE ' + QUOTENAME(SCHEMA_NAME) + '.' + QUOTENAME(OBJECT_NAME) + ' DROP CONSTRAINT ' + QUOTENAME(index_name) + ';'
    ELSE 'DROP INDEX ' + +QUOTENAME(index_name) + ' ON ' + QUOTENAME(SCHEMA_NAME) + '.' + QUOTENAME(OBJECT_NAME)  + ';'
  END COLLATE database_default AS c1,
  CASE
    WHEN is_primary_key = 1
    THEN 'ALTER TABLE ' + QUOTENAME(SCHEMA_NAME) + '.' + QUOTENAME(OBJECT_NAME) + ' ADD CONSTRAINT ' + QUOTENAME(index_name) + ' PRIMARY KEY ' 
         + CASE
             WHEN type_desc = 'CLUSTERED'
             THEN type_desc
             ELSE ''
           END + ' (' + index_columns_key + ')' + ';'
    WHEN is_unique_constraint = 1
    THEN 'ALTER TABLE ' + QUOTENAME(SCHEMA_NAME) + '.' + QUOTENAME(OBJECT_NAME) + ' ADD CONSTRAINT ' + QUOTENAME(index_name) + 'UNIQUE (' + index_columns_key + ')' + ';'
    --ELSE 'DROP INDEX IX_ProductVendor_BusinessEntityID  ON Purchasing.ProductVendor WITH (ONLINE = ON, MAXDOP = 2)'
    ELSE 'CREATE INDEX ' + +QUOTENAME(index_name) + ' ON ' + +QUOTENAME(SCHEMA_NAME) + '.' + QUOTENAME(OBJECT_NAME) + ' (' + index_columns_key + ')'
    + CASE
         WHEN index_columns_include = '---'
         THEN ''
         ELSE ' INCLUDE (' + index_columns_include + ')'
       END 
    + CASE
         WHEN has_filter = 0
         THEN ''
         ELSE ' WHERE ' + filter_definition + ' '
       END   + ';'
  END COLLATE database_default AS c2,
  *
INTO
  #INDEXES
FROM   (SELECT
          SCH.schema_id,
          SCH.[name] COLLATE database_default AS SCHEMA_NAME,
          OBJS.[object_id],
          OBJS.[name] COLLATE database_default AS OBJECT_NAME,
          IDX.index_id,
          ISNULL(IDX.[name], '---') COLLATE database_default AS index_name,
          partitions.Rows,
          partitions.SizeMB,
          INDEXPROPERTY(OBJS.[object_id], IDX.[name], 'IndexDepth') AS IndexDepth,
          IDX.type,
          IDX.type_desc COLLATE database_default AS type_desc,
          IDX.fill_factor,
          IDX.is_unique,
          IDX.is_primary_key,
          IDX.is_unique_constraint,
          IDX.has_filter,
          IDX.filter_definition,
          ISNULL(Index_Columns.index_columns_key, '---') COLLATE database_default AS index_columns_key,
          ISNULL(Index_Columns.index_columns_include, '---') COLLATE database_default AS index_columns_include
        FROM   sys.objects OBJS
               INNER JOIN sys.schemas SCH
                 ON OBJS.schema_id = SCH.schema_id
               INNER JOIN sys.indexes IDX
                 ON OBJS.[object_id] = IDX.[object_id]
               INNER JOIN (SELECT
                             [OBJECT_ID],
                             index_id,
                             SUM(row_count) AS ROWS,
                             CONVERT(NUMERIC(19, 3), CONVERT(NUMERIC(19, 3), SUM(in_row_reserved_page_count+lob_reserved_page_count+row_overflow_reserved_page_count))/CONVERT(NUMERIC(19, 3), 128)) AS SizeMB
                           FROM   sys.dm_db_partition_stats STATS
                           GROUP  BY
                            [OBJECT_ID],
                            index_id) AS partitions
                 ON IDX.[object_id] = partitions.[object_id]
                    AND IDX.index_id = partitions.index_id
               CROSS APPLY (SELECT
                              LEFT(index_columns_key, LEN(index_columns_key) - 1) COLLATE database_default AS index_columns_key,
                              LEFT(index_columns_include, LEN(index_columns_include) - 1) COLLATE database_default AS index_columns_include
                            FROM   (SELECT
                                      (SELECT
                                         colz.[name] + ',' + ' ' COLLATE database_default
                                       FROM   sys.index_columns IXCOLS
                                              INNER JOIN sys.columns colz
                                                ON IXCOLS.column_id = colz.column_id
                                                   AND IXCOLS.[object_id] = colz.[object_id]
                                       WHERE  IXCOLS.is_included_column = 0
                                          AND IDX.[object_id] = IXCOLS.[object_id]
                                          AND IDX.index_id = IXCOLS.index_id
                                       ORDER  BY
                                        key_ordinal
                                       FOR XML PATH('')) AS index_columns_key,
                                      (SELECT
                                         colz.[name] + ',' + ' ' COLLATE database_default
                                       FROM   sys.index_columns IXCOLS
                                              INNER JOIN sys.columns colz
                                                ON IXCOLS.column_id = colz.column_id
                                                   AND IXCOLS.[object_id] = colz.[object_id]
                                       WHERE  IXCOLS.is_included_column = 1
                                          AND IDX.[object_id] = IXCOLS.[object_id]
                                          AND IDX.index_id = IXCOLS.index_id
                                       ORDER  BY
                                        index_column_id
                                       FOR XML PATH('')) AS index_columns_include) AS Index_Columns) AS Index_Columns)AllIndexes

--################################################################################################# 
--STEP_005 primary keys
--################################################################################################# 
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  50 AS ExecutionOrder,
  IDXZ.c1 AS Command
FROM   #Indexes IDXZ
       LEFT OUTER JOIN #MyAffectedTables TBLZ
         ON IDXZ.object_name = TBLZ.TableName
WHERE  is_primary_key = 1
   AND ( CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_key + ',') > 0
          OR CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_include + ',') > 0 )

INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  500 AS ExecutionOrder,
  IDXZ.c2 AS Command
FROM   #Indexes IDXZ
       LEFT OUTER JOIN #MyAffectedTables TBLZ
         ON IDXZ.object_name = TBLZ.TableName
WHERE  is_primary_key = 1
   AND ( CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_key + ',') > 0
          OR CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_include + ',') > 0 )

--################################################################################################# 
--STEP_006 unique indexes
--################################################################################################# 
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  60 AS ExecutionOrder,
  IDXZ.c1 AS Command
FROM   #Indexes IDXZ
       LEFT OUTER JOIN #MyAffectedTables TBLZ
         ON IDXZ.object_name = TBLZ.TableName
WHERE  IDXZ.is_primary_key = 0
   AND IDXZ.is_unique_constraint = 0
   AND ( CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_key + ',') > 0
          OR CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_include + ',') > 0 )

INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  600 AS ExecutionOrder,
  IDXZ.c2 AS Command
FROM   #Indexes IDXZ
       LEFT OUTER JOIN #MyAffectedTables TBLZ
         ON IDXZ.object_name = TBLZ.TableName
WHERE  IDXZ.is_primary_key = 0
   AND IDXZ.is_unique_constraint = 0
   AND ( CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_key + ',') > 0
          OR CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_include + ',') > 0 )

--################################################################################################# 
--STEP_007 regular indexes(also featuring includes or filtered indexes
--################################################################################################# 
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  70 AS ExecutionOrder,
  IDXZ.c1 AS Command
FROM   #Indexes IDXZ
       LEFT OUTER JOIN #MyAffectedTables TBLZ
         ON IDXZ.object_name = TBLZ.TableName
WHERE  IDXZ.is_primary_key = 0
   AND IDXZ.is_unique_constraint = 1
   AND ( CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_key + ',') > 0
          OR CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_include + ',') > 0 )

INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  700 AS ExecutionOrder,
  IDXZ.c2 AS Command
FROM   #Indexes IDXZ
       LEFT OUTER JOIN #MyAffectedTables TBLZ
         ON IDXZ.object_name = TBLZ.TableName
WHERE  IDXZ.is_primary_key = 0
   AND IDXZ.is_unique_constraint = 1
   AND ( CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_key + ',') > 0
          OR CHARINDEX(TBLZ.ColumnName + ',', IDXZ.index_columns_include + ',') > 0 )

--################################################################################################# 
--STEP_008 Column Collation definitions
--################################################################################################# 
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT
  DISTINCT
  80 AS ExecutionOrder,
  'ALTER TABLE ' + QUOTENAME(SCHEMA_NAME(objz.schema_id)) + '.' + QUOTENAME(objz.name) + ' ALTER COLUMN ' 
  + CASE
        WHEN colz.[is_computed] = 0
        THEN QUOTENAME(colz.[name]) + ' ' + ( TYPE_NAME(colz.[user_type_id]) ) 
             + CASE
               WHEN TYPE_NAME(colz.[user_type_id]) IN ( 'char', 'varchar' )
               THEN
                 CASE
                   WHEN colz.[max_length] = -1
                   THEN '(max)' + SPACE(6 - LEN(CONVERT(VARCHAR, colz.[max_length]))) + SPACE(7) + SPACE(16 - LEN(TYPE_NAME(colz.[user_type_id])))
                         ----collate to comment out when not desired
                         + CASE
                             WHEN colz.collation_name IS NULL
                             THEN ''
                             ELSE ' COLLATE ' + @NewCollation -- this was the old collation: colz.collation_name
                           END + CASE
                                   WHEN colz.[is_nullable] = 0
                                   THEN ' NOT NULL'
                                   ELSE '     NULL'
                                 END
                   ELSE '(' + CONVERT(VARCHAR, colz.[max_length]) + ') ' + SPACE(6 - LEN(CONVERT(VARCHAR, colz.[max_length]))) + SPACE(7) + SPACE(16 - LEN(TYPE_NAME(colz.[user_type_id])))
                         ----collate to comment out when not desired
                         + CASE
                              WHEN colz.collation_name IS NULL
                              THEN ''
                              ELSE ' COLLATE ' + @NewCollation
                            END
                         + CASE
                             WHEN colz.[is_nullable] = 0
                             THEN ' NOT NULL'
                             ELSE '     NULL'
                           END
                 END
               WHEN TYPE_NAME(colz.[user_type_id]) IN ( 'nchar', 'nvarchar' )
               THEN
                 CASE
                   WHEN colz.[max_length] = -1
                   THEN '(max)' + SPACE(6 - LEN(CONVERT(VARCHAR, (colz.[max_length])))) + SPACE(7) + SPACE(16 - LEN(TYPE_NAME(colz.[user_type_id])))
                         ----collate to comment out when not desired
                         --+ CASE
                         --     WHEN colz.collation_name IS NULL
                         --     THEN ''
                         --     ELSE ' COLLATE ' + colz.collation_name
                         --   END
                         + CASE
                             WHEN colz.[is_nullable] = 0
                             THEN ' NOT NULL'
                             ELSE '     NULL'
                           END
                   ELSE '(' + CONVERT(VARCHAR, (colz.[max_length])) + ') ' + SPACE(6 - LEN(CONVERT(VARCHAR, (colz.[max_length])))) + SPACE(7) + SPACE(16 - LEN(TYPE_NAME(colz.[user_type_id])))
                         ----collate to comment out when not desired
                         --+ CASE
                         --     WHEN colz.collation_name IS NULL
                         --     THEN ''
                         --     ELSE ' COLLATE ' + colz.collation_name
                         --   END
                         + CASE
                             WHEN colz.[is_nullable] = 0
                             THEN ' NOT NULL'
                             ELSE '     NULL'
                           END
                 END
             END
      END --iscomputed = 0
   + ';' AS Command 
FROM   sys.columns colz 
       LEFT OUTER JOIN sys.tables objz
         ON colz.object_id = objz.object_id
INNER JOIN #MyAffectedTables tabz  
ON   tabz.object_id = colz.object_id
   AND tabz.column_id = colz.column_id
WHERE  objz.type = 'U'
   AND TYPE_NAME(colz.[user_type_id]) IN ( 'char', 'varchar', 'nchar', 'nvarchar' )

--################################################################################################# 
--STEP_009 refresh dependent views, procs and functions
-- refresh them in dependancy order in a single pass.
--################################################################################################# 
--if there was nothing with the wrong collation, there's no need to refresh:
IF EXISTS(SELECT * FROM #Results WHERE ExecutionOrder > 0)
  BEGIN
  CREATE TABLE #MyObjectHierarchy 
   (
    HID int identity(1,1) not null primary key,
    ObjectId int,
    TYPE int,OBJECTTYPE AS CASE 
                             WHEN TYPE =  1 THEN 'FUNCTION' 
                             WHEN TYPE =  4 THEN 'VIEW' 
                             WHEN TYPE =  8 THEN 'TABLE' 
                             WHEN TYPE = 16 THEN 'PROCEDURE'
                             WHEN TYPE =128 THEN 'RULE'
                             ELSE ''
                           END,
   ONAME varchar(255), 
   OOWNER varchar(255), 
   SEQ int
   )

  --our list of objects in dependancy order
  INSERT #MyObjectHierarchy (TYPE,ONAME,OOWNER,SEQ)
-- use this if inside a stored procedure
-- EXEC sp_msdependencies @intrans = 1 
--else
   EXEC sp_msdependencies 
    
INSERT INTO #Results
            (ExecutionOrder,Command)
SELECT 
  900 + HID AS ExecutionOrder,
  CASE 
    WHEN OBJECTTYPE = 'VIEW'
    THEN 'EXEC sp_refreshview ''' + QUOTENAME(OOWNER) + '.' + QUOTENAME(ONAME) + ''';'
    WHEN OBJECTTYPE IN ('FUNCTION' ,'PROCEDURE')
    THEN 'EXEC sp_recompile  ''' + QUOTENAME(OOWNER) + '.' + QUOTENAME(ONAME) + ''';'
  END
FROM #MyObjectHierarchy 
WHERE OBJECTTYPE IN('FUNCTION','VIEW','PROCEDURE') 
ORDER BY HID 
  END --Exists 

--################################################################################################# 
--Final Presentation
--#################################################################################################     
SELECT
  *
FROM   #Results
ORDER  BY
  ExecutionOrder,
  ID
--#################################################################################################     
--optional cursor to go ahead and run all these scripts
--don't run this cursor unless you are 100% sure of the scripts.
--TEST TEST TEST!
--#################################################################################################     
/*
declare
  @isql varchar(max)
  
  declare c1 cursor LOCAL FORWARD_ONLY STATIC READ_ONLY for
  --###############################################################################################
  --cursor definition
  --###############################################################################################
  SELECT
    Command
  FROM   #Results
  ORDER  BY
    ExecutionOrder,
    ID
  --###############################################################################################
  open c1
  fetch next from c1 into @isql
  While @@fetch_status <> -1
    begin
    print @isql
    exec(@isql)
    fetch next from c1 into @isql
    end
  close c1
  deallocate c1
*/
--#################################################################################################    
--clean up our temp objects
--#################################################################################################
IF (SELECT
      OBJECT_ID('Tempdb.dbo.#MyAffectedTables')) IS NOT NULL
  DROP TABLE #MyAffectedTables
IF (SELECT
      OBJECT_ID('Tempdb.dbo.#Indexes')) IS NOT NULL
  DROP TABLE #Indexes

IF (SELECT
      OBJECT_ID('Tempdb.dbo.#Results')) IS NOT NULL
  DROP TABLE #Results 

IF (SELECT
      OBJECT_ID('Tempdb.dbo.#MyObjectHierarchy')) IS NOT NULL
  DROP TABLE #MyObjectHierarchy 

Grab a copy of one of your databases, the more complex the better. Try it out for yourself, and join the discussion on this article and report your results! Any feedback you give will make the SQL community as a whole a lot better.

There’s always room for improvement. There’s SQL code I wrote last week that I might refactor or make better today.  

 

Resources:

change_collationFull.sql
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