Postgresql 简明教程

PostgreSQL - Useful Functions

PostgreSQL 内置函数，也称为聚合函数，用于对字符串或数字数据执行处理。

PostgreSQL built-in functions, also called as Aggregate functions, are used for performing processing on string or numeric data.

以下是所有通用 PostgreSQL 内置函数的列表 -

The following is the list of all general-purpose PostgreSQL built-in functions −

  1. PostgreSQL COUNT Function − The PostgreSQL COUNT aggregate function is used to count the number of rows in a database table.

  2. PostgreSQL MAX Function − The PostgreSQL MAX aggregate function allows us to select the highest (maximum) value for a certain column.

  3. PostgreSQL MIN Function − The PostgreSQL MIN aggregate function allows us to select the lowest (minimum) value for a certain column.

  4. PostgreSQL AVG Function − The PostgreSQL AVG aggregate function selects the average value for certain table column.

  5. PostgreSQL SUM Function − The PostgreSQL SUM aggregate function allows selecting the total for a numeric column.

  6. PostgreSQL ARRAY Functions − The PostgreSQL ARRAY aggregate function puts input values, including nulls, concatenated into an array.

  7. PostgreSQL Numeric Functions − Complete list of PostgreSQL functions required to manipulate numbers in SQL.

  8. PostgreSQL String Functions − Complete list of PostgreSQL functions required to manipulate strings in PostgreSQL.