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Oracle CASE Statement

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In Oracle Database, the CASE statement compares a list of conditions and returns one of multiple possible expressions.

Oracle Database’s CASE statement is very similar to the CASE expression (which is defined in the SQL standard (ISO/IEC 9075)). However, Oracle supports both the CASE expression and the CASE statement, and there’s a distinction between the two. The CASE statement can be used to execute of a sequence of PL/SQL statements, whereas the CASE expression returns a single value. Also, there’s a difference in how they deal with the lack of an ELSE clause when a condition is not met.

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Oracle CASE Expression

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In Oracle Database, the CASE expression compares a list of conditions and returns one of multiple possible expressions. It allows us to use IF … THEN … ELSE logic in SQL statements without having to invoke procedures.

The CASE expression is included in the SQL standard (ISO/IEC 9075), and most major RDBMSs support it.

Oracle also has a CASE statement that’s very similar to the CASE expression, but with some minor differences.

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SQL ISNULL() Explained

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Some RDBMSs provide an ISNULL() function that can be used when dealing with potentially null values.

MySQL, MariaDB, and Oracle Database each have an ISNULL() function that returns 1 if its argument is null, and 0 if it’s not.

SQL Server also has an ISNULL() function, but it works differently. It works more like how the IFNULL() function works in some other RDBMSs.

Other RDBMSs, such as PostgreSQL and SQLite don’t include an ISNULL() function, but they do support the IS NULL predicate (as do the other RDBMSs).

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MySQL CASE Statement

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In MySQL, the CASE statement can be used in stored programs to perform a complex conditional construct. It compares a list of conditions and returns a different result depending on which condition (if any) is matched.

The CASE statement is different to the CASE operator, in that the CASE statement is specifically for use in stored programs. Also, there’s a slight difference in the syntax.

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MySQL CASE Operator

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In MySQL, the CASE operator compares a list of conditions and returns one of multiple possible result expressions.

The CASE expression is included in the SQL standard (ISO/IEC 9075), and most major RDBMSs support it.

MySQL also has the CASE statement, which is slightly different to the CASE operator. This article is about the CASE operator.

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MariaDB CASE Operator

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In MariaDB, we can use the CASE operator to compare a list of conditions and return a different result depending on which condition (if any) is matched.

The CASE expression is included in the SQL standard (ISO/IEC 9075), and most major RDBMSs support it.

MariaDB also has the CASE statement, which is slightly different to the CASE operator. This article is about the CASE operator.

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