以下是 MySQL 中常用的条件语句，全部以小写形式列出并说明：
1. 基础比较条件
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=：等于sql
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select * from users where age = 25; -
<>或!=：不等于sql
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select * from products where price <> 100; -
>：大于sql
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select * from orders where amount > 1000; -
<：小于sql
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select * from students where score < 60; -
>=：大于等于sql
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select * from employees where salary >= 5000; -
<=：小于等于sql
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select * from inventory where quantity <= 10;
2. 范围条件
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between ... and ...：在某个范围内（包含边界）sql
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select * from products where price between 50 and 100; -
not between ... and ...：不在某个范围内sql
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select * from employees where salary not between 3000 and 6000;
3. 集合条件
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in (...)：在指定值列表中sql
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select * from customers where id in (1, 3, 5); -
not in (...)：不在指定值列表中sql
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select * from cities where country_code not in ('US', 'CA');
4. 模糊匹配条件
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like：模式匹配sql
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select * from users where name like 'john%'; -
not like：不匹配模式sql
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select * from products where name not like '%test%'; -
regexp或rlike：正则表达式匹配sql
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select * from articles where title regexp '^[0-9]'; -
not regexp：不匹配正则表达式sql
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select * from logs where message not regexp 'error';
5. 空值判断条件
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is null：是空值sql
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select * from orders where shipped_date is null; -
is not null：不是空值sql
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select * from employees where manager_id is not null;
6. 逻辑组合条件
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and：逻辑与sql
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select * from products where price > 100 and stock > 0; -
or：逻辑或sql
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select * from users where age < 18 or age > 65; -
not：逻辑非sql
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select * from customers where not (status = 'inactive'); -
xor：逻辑异或（MySQL特有）sql
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select * from permissions where read xor write;
7. 特殊条件
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exists (...)：子查询返回结果存在sql
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select * from departments d where exists (select 1 from employees e where e.dept_id = d.id); -
not exists (...)：子查询返回结果不存在sql
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select * from products p where not exists (select 1 from inventory i where i.product_id = p.id); -
case ... when ... then ... else ... end：条件选择sql
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select name, case when score >= 90 then 'A' when score >= 80 then 'B' else 'C' end as grade from students;
8. JSON条件（MySQL 5.7+）
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json_contains：JSON包含特定值sql
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select * from products where json_contains(tags, '"sale"'); -
json_contains_path：JSON包含特定路径sql
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select * from users where json_contains_path(profile, 'one', '$.address.city');
