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MySQL 教程

MySQL 主页 MySQL 简介 MySQL RDBMS

MySQL SQL

MySQL SQL MySQL SELECT MySQL WHERE MySQL AND, OR, NOT MySQL ORDER BY MySQL INSERT INTO MySQL NULL 值 MySQL UPDATE MySQL DELETE MySQL LIMIT MySQL MIN 和 MAX MySQL COUNT, AVG, SUM MySQL LIKE MySQL 通配符 MySQL IN MySQL BETWEEN MySQL 别名 MySQL 联接 MySQL INNER JOIN MySQL LEFT JOIN MySQL RIGHT JOIN MySQL CROSS JOIN MySQL 自联接 MySQL UNION MySQL GROUP BY MySQL HAVING MySQL EXISTS MySQL ANY, ALL MySQL INSERT SELECT MySQL CASE MySQL Null 函数 MySQL 注释 MySQL 运算符

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MySQL 参考

MySQL 数据类型 MySQL 函数
字符串函数 ASCII CHAR_LENGTH CHARACTER_LENGTH CONCAT CONCAT_WS FIELD FIND_IN_SET FORMAT INSERT INSTR LCASE LEFT LENGTH LOCATE LOWER LPAD LTRIM MID POSITION REPEAT REPLACE REVERSE RIGHT RPAD RTRIM SPACE STRCMP SUBSTR SUBSTRING SUBSTRING_INDEX TRIM UCASE UPPER 数值函数 ABS ACOS ASIN ATAN ATAN2 AVG CEIL CEILING COS COT COUNT DEGREES DIV EXP FLOOR GREATEST LEAST LN LOG LOG10 LOG2 MAX MIN MOD PI POW POWER RADIANS RAND ROUND SIGN SIN SQRT SUM TAN TRUNCATE 日期函数 ADDDATE ADDTIME CURDATE CURRENT_DATE CURRENT_TIME CURRENT_TIMESTAMP CURTIME DATE DATEDIFF DATE_ADD DATE_FORMAT DATE_SUB DAY DAYNAME DAYOFMONTH DAYOFWEEK DAYOFYEAR EXTRACT FROM_DAYS HOUR LAST_DAY LOCALTIME LOCALTIMESTAMP MAKEDATE MAKETIME MICROSECOND MINUTE MONTH MONTHNAME NOW PERIOD_ADD PERIOD_DIFF QUARTER SECOND SEC_TO_TIME STR_TO_DATE SUBDATE SUBTIME SYSDATE TIME TIME_FORMAT TIME_TO_SEC TIMEDIFF TIMESTAMP TO_DAYS WEEK WEEKDAY WEEKOFYEAR YEAR YEARWEEK 高级函数 BIN BINARY CASE CAST COALESCE CONNECTION_ID CONV CONVERT CURRENT_USER DATABASE IF IFNULL ISNULL LAST_INSERT_ID NULLIF SESSION_USER SYSTEM_USER USER VERSION

MySQL 例子

MySQL 例子 MySQL 编辑器 MySQL 测验 MySQL 练习 MySQL 证书

MySQL IF() 函数

❮ MySQL 函数

例子

如果条件为 TRUE，则返回 "YES"，如果条件为 FALSE，则返回 "NO"

SELECT IF(500<1000, "YES", "NO");
自己尝试 »

定义和用法

IF() 函数在条件为 TRUE 时返回一个值，或在条件为 FALSE 时返回另一个值。

语法

IF(condition, value_if_true, value_if_false)

参数值

参数 描述
条件 必需。要测试的值
value_if_true 必需。如果条件为 TRUE，则返回的值
value_if_false 必需。如果条件为 FALSE，则返回的值

技术细节

适用于 从 MySQL 4.0 开始

更多示例

例子

如果条件为 TRUE，则返回 5，如果条件为 FALSE，则返回 10

SELECT IF(500<1000, 5, 10);
自己尝试 »

例子

测试两个字符串是否相同，如果相同则返回“YES”，否则返回“NO”

SELECT IF(STRCMP("hello","bye") = 0, "YES", "NO");
自己尝试 »

例子

如果条件为 TRUE，则返回“MORE”，如果条件为 FALSE，则返回“LESS”

SELECT OrderID, Quantity, IF(Quantity>10, "MORE", "LESS")
FROM OrderDetails;
自己尝试 »

❮ MySQL 函数

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