单行函数-SQL语言基础

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文件名称：单行函数-SQL语言基础
文件大小：5.26MB
文件格式：PPT
更新时间：2021-04-25 19:38:12
SQL 基础 单行函数 * function_name (column|expression, [arg1, arg2,...]) 操作数据项 接收参数并返回一个值 在返回的每一行上进行处理 每一行都有一个处理结果 可能要修改数据类型 可以进行嵌套 接受多个参数，参数可以是一个列或者一个表达式 * Single-Row Functions Single-row functions are used to manipulate data items. They accept one or more arguments and return one value for each row returned by the query. An argument can be one of the following: User-supplied constant Variable value Column name Expression Features of single-row functions: Act on each row returned in the query Return one result per row May return a data value of a different type than that referenced May expect one or more arguments Can be used in SELECT, WHERE, and ORDER BY clauses; can be nested In the syntax: function_name is the name of the function column is any named database column expression is any character string or calculated expression arg1, arg2 is any argument to be used by the function