PostgreSQL – Useful Functions PostgreSQL built-in functions, also called as Aggregate functions, are used for performing processing on string or numeric data. The following is the list of all general-purpose PostgreSQL built-in functions − − The PostgreSQL COUNT aggregate function is used to count the number of rows in a database table. − The PostgreSQL […]
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PostgreSQL – UNIONS Clause The PostgreSQL UNION clause/operator is used to combine the results of two or more SELECT statements without returning any duplicate rows. To use UNION, each SELECT must have the same number of columns selected, the same number of column expressions, the same data type, and have them in the same order […]
PostgreSQL – NULL Values The PostgreSQL NULL is the term used to represent a missing value. A NULL value in a table is a value in a field that appears to be blank. A field with a NULL value is a field with no value. It is very important to understand that a NULL value […]