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知乎专栏多维度架构

第 63 章 Functions and Operators

目录

63.1. COUNT
63.2. group_concat() 列传行
63.3. UUID()
63.4. String
63.4.1. LEFT/RIGHT
63.4.2. RPAD/LPAD
63.4.3. CONCAT
63.4.4. CONCAT_WS
63.4.5. 链接所有字段
63.4.6. GROUP_CONCAT
63.4.7. replace
63.4.8. SUBSTRING
63.4.9. SUBSTRING_INDEX
63.4.10. AES_ENCRYPT / AES_DECRYPT
63.5. Date and Time
63.5.1. year/month/day hour:minite:second
63.5.2. Unix time
63.5.3. DATE_FORMAT
63.5.4. DATE_SUB/DATE_ADD
63.5.5. datediff / timediff
63.6. 数值函数
63.6.1. cast 类型转换
63.6.2. truncate 保留小数位数
63.6.3. MOD 求余
63.7. Control Flow Functions

63.1. COUNT

count()

SELECT (SELECT count(1) FROM ecs_category) as 'Export category count',
	(SELECT count(1) FROM ecs_goods) as 'Goods count',
	(SELECT count(1) FROM ecs_goods_attr) as 'Attr count';