数据库及 SQL

CURD

INSERT INTO tableName (column1, column2, ...) VALUES (valu1, value2, ...)

UPDATE tableName SET feild = newValue, feild2 = newValue2 WHERE ...

条件

# 空
WHERE feild IS null
WHERE feild = ''
# 日期
created_at > '2019-11-05 00:00:00'

find_in_set

JOIN

拼接

CONCAT(str1, str2, ...)
# 可能会数学计算
feild + feild

https://www.cnblogs.com/apolloren/p/11002449.html

运算

加减

feild + feild
feild - feild

日期格式

FORMAT(feild, 'YYYY-MM-DD')

MySQL DATE_FORMAT() 函数