ISNULL function behaves differently in MySQL and Microsoft SQL Server.
In MySQL, ISNULL tests whether the given expression is NULL. It returns 1 if the expression is NULL otherwise it returns 0.
However, in SQL Server, the null values are replaced with user-defined values during the expression evaluation process.
Look at the below examples:
MySQL:
SELECT ISNULL(NULL);
It returns: 1
SQL Server:
SELECT ISNULL(NULL,’SomethingElse’);
It returns: SomethingElse
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