T-SQL

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Picking the ON or WHERE Clause for the SQL Predicate

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Helping people solve T-SQL problems is one of my favorite hobbies. Someone messaged me the other day with a complex query that was almost complete except for one issue. He needed to perform a LEFT OUTER JOIN but had to filter based on a value from the right table. However, when he added the filter, SQL removed rows from the left table. The task was to decide where to place the SQL predicate: in the ON or WHERE clause.

2025-09-01

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Question of the Day

Multiple Values Inserted

I have this code on SQL Server 2022. What happens when it runs all at once? 

DROP TABLE IF EXISTS dbo.Commission
GO
CREATE TABLE dbo.Commission
(id INT NOT NULL IDENTITY(1,1) CONSTRAINT CommissionPK PRIMARY KEY
, salesperson VARCHAR(20)
, commission VARCHAR(20)
)
GO
INSERT dbo.Commission
( salesperson, commission)
VALUES
( 'Brian', 12 ),
( 'Brian', 'None' )
GO
 

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