文件名称：选择查询出的行-SQL语言基础
文件大小：5.26MB
文件格式：PPT
更新时间：2024-05-15 13:24:49
SQL 基础
选择查询出的行 * SELECT [DISTINCT] {*| column [alias], ...} FROM table [WHERE condition(s)]; 用where子句限定查询出的行. Where子句紧跟在From子句之后. * 条件最常见的形式是由变量、常量和比较运算符组成。 Limiting Rows Selected You can restrict the rows returned from the query by using the WHERE clause. A WHERE clause contains a condition that must be met, and it directly follows the FROM clause. In the syntax: WHERE restricts the query to rows that meet a condition condition is composed of column names, expressions, constants, and a comparison operator The WHERE clause can compare values in columns, literal values, arithmetic expressions, or functions. The WHERE clause consists of three elements: Column name Comparison operator Column name, constant, or list of values