条件查询语法

FROM mytable
WHERE condition
AND/OR another_condition
AND/OR …;

新增 LIKE(模糊查询) 和 %(通配符)

Operator(操作符)Condition(解释)Example(例子)
=Case sensitive exact string comparison (notice the single equals)完全等于col_name = "abc"
!= or <>Case sensitive exact string inequality comparison 不等于col_name != "abcd"
LIKECase insensitive exact string comparison 没有用通配符等价于 =col_name LIKE "ABC"
NOT LIKECase insensitive exact string inequality comparison 没有用通配符等价于 !=col_name NOT LIKE "ABCD"
%Used anywhere in a string to match a sequence of zero or more characters (only with LIKE or NOT LIKE) 通配符,代表匹配0个以上的字符col_name LIKE "%AT%"<br/>(matches "AT", "ATTIC", "CAT" or even "BATS") "%AT%" 代表AT 前后可以有任意字符
_Used anywhere in a string to match a single character (only with LIKE or NOT LIKE) 和% 相似,代表1个字符col_name LIKE "AN_"<br/>(matches "AND", but not "AN")
IN (…)String exists in a list 在列表col_name IN ("A", "B", "C")
NOT IN (…)String does not exist in a list 不在列表col_name NOT IN ("D", "E", "F")

在字符串表达式中的字符串需要用引号 " 包含,如果不用引号,SQL会认为是一个属性列的名字,如:col_name = color 表示 col_name和color两个属性一样的行 col_name = "color" 表示 col_name 属性为字符串 "color"的行.

最后修改:2021 年 03 月 17 日 02 : 04 AM
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