The BIT data type is an awkward fit for a SQL database. It doesn't have just two values, and it can do unexpected things in expressions. What is worse, it is a flag rather than a predicate, and so its overuse, along with bit masks, is a prime candidate for being listed as a 'SQL Code Smell'. Joe Celko makes the case.
2011-01-24
3,676 reads
LINQ is one of the few technologies that you can start to use without a lot of preliminary learning. Also, it lends itself to learning by trying out examples. With Michael Sorens' help, you can watch as your conventional C# code changes to ravenous LINQ before your very eyes.
2011-01-21
3,948 reads
Did you ever wonder how and why your indexes affect the performances of joins? Once you've read Fabiano Amorim's unforgettable explanation, you'll learn to love the MERGE operator, and plan your indexes so as to allow the Query Optimiser to use it.
2011-01-20
3,194 reads
When one considers the amount of time and effort that Unit Testing consumes for the Database Developer, is surprising how few good SQL Server Test frameworks are around. tSQLt , which is open source and free to use, is one of the frameworks that provide a simple way to populate a table with test data as part of the unit test, and check the results with what should be expected. Sebastian Meine and Dennis Lloyd, who created tSQLt, explain
2011-01-19
3,084 reads
While the system procedure sp_MSforeachdb is neither documented nor officially supported, most SQL Server professionals have used it at one time or another. This is typically for ad hoc maintenance tasks, but many people (myself included) have used this type of looping activity in permanent routines. Sadly, I have discovered instances where, under heavy load and/or with a large number of databases, the procedure can actually skip multiple catalogs with no error or warning message. Since this situation is not easily reproducible, and since Microsoft typically has no interest in fixing unsupported objects, this may be happening in your environment right now
2011-01-18
3,580 reads
As a guideline, clustered Indexes should be Narrow, Unique, Static and Ever Increasing (NUSE). Michelle Ufford Explains why.
2011-01-17
4,641 reads
SQL Azure provides features similar to a relational database for your cloud apps. We’ll show you how to start developing for SQL Azure today.
2011-01-14
3,003 reads
I'd seen you posted a tip on capturing SQL based PerfMon counters using sys.dm_os_performance_counters. What queries can I run against those stored results that would allow me to examine memory usage on my SQL instance?
2011-01-13
2,548 reads
Most of the time, you do not have to worry about implicit conversion in SQL expressions, or when assigning a value to a column. Just occasionally, though, you'll find that data gets truncated, queries run slowly, or comparisons just seem plain wrong. Robert Sheldon explains why you sometimes need to be very careful if you mix data types when manipulating values.
2011-01-12
4,537 reads
It is always more efficient to maintain referential integrity by using constraints rather than triggers. Sometimes it isn't obvious how to do this. Until a recent idea by Alex Kuznetsov, the history table presented problems for checking data that were difficult to solve with constraints. Joe Celko explains.
2011-01-11
3,294 reads
By Brian Kelley
I will be leading an in-person Certified Information Systems Auditor (CISA) exam prep class...
EightKB is back again for 2026! The biggest online SQL Server internals conference is...
By HeyMo0sh
Working in DevOps long enough teaches you two universal truths: That’s exactly why I...
Hi all, I just started using VS Code to work with DB projects. I...
Comments posted to this topic are about the item Fun with JSON II
Comments posted to this topic are about the item Changing Data Types
I have some data in a table:
CREATE TABLE #test_data
(
id INT PRIMARY KEY,
name VARCHAR(100),
birth_date DATE
);
-- Step 2: Insert rows
INSERT INTO #test_data
VALUES
(1, 'Olivia', '2025-01-05'),
(2, 'Emma', '2025-03-02'),
(3, 'Liam', '2025-11-15'),
(4, 'Noah', '2025-12-22');
If I run this query, how many rows are returned?
SELECT t1.[key] AS row,
t2.*
FROM OPENJSON(
(
SELECT t.* FROM #test_data AS t FOR JSON PATH
)
) t1
CROSS APPLY OPENJSON(t1.value) t2; See possible answers