以下是一些常用的MySQL查询语句示例:
基本查询:
- 查询所有记录:
SELECT * FROM table_name;
- 查询特定列:
SELECT column1, column2 FROM table_name;
- 带条件查询:
SELECT * FROM table_name WHERE condition;
- 去重查询:
SELECT DISTINCT column FROM table_name;
- 查询所有记录:
排序和限制:
- 排序:
SELECT * FROM table_name ORDER BY column ASC/DESC;
- 限制记录数:
SELECT * FROM table_name LIMIT count;
- 排序:
条件查询:
- 等于:
=
- 不等于:
!=
或<>
- 大于:
>
- 小于:
<
- 大于等于:
>=
- 小于等于:
<=
- 区间查询:
BETWEEN value1 AND value2
- 模糊查询:
LIKE 'pattern'
- 空值判断:
IS NULL
或IS NOT NULL
- 多条件:
AND
,OR
- 等于:
聚合函数:
- 平均值:
SELECT AVG(column) FROM table_name;
- 总和:
SELECT SUM(column) FROM table_name;
- 最大值:
SELECT MAX(column) FROM table_name;
- 最小值:
SELECT MIN(column) FROM table_name;
- 计数:
SELECT COUNT(column) FROM table_name;
- 平均值:
分组和聚合:
- 分组:
SELECT column1, SUM(column2) FROM table_name GROUP BY column1;
- 过滤分组:
HAVING condition;
- 分组:
连接查询:
- 内连接:
SELECT * FROM table1 INNER JOIN table2 ON condition;
- 左连接:
SELECT * FROM table1 LEFT JOIN table2 ON condition;
- 右连接:
SELECT * FROM table1 RIGHT JOIN table2 ON condition;
- 内连接:
子查询:
- 子查询作为列:
SELECT column, (SELECT MAX(column2) FROM table2) FROM table1;
- 子查询作为条件:
SELECT * FROM table1 WHERE column IN (SELECT column2 FROM table2);
- 子查询作为列:
更新和删除:
- 更新记录:
UPDATE table_name SET column1 = value1, column2 = value2 WHERE condition;
- 删除记录:
DELETE FROM table_name WHERE condition;
- 更新记录:
以上是一些常用的MySQL查询语句示例,可以根据实际需求进行适当的组合和修改。