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SELECT * FROM tableName; 选择 tableName 中的所有列。

SELECT column1, column2 FROM tableName; 选择 column1, column2 列。

SELECT column1 FROM tableName; 选择 column1 列。

SELECT DISTINCT column1 FROM tableName; 结果去重。

SELECT column1 FROM tableName LIMIT 5; 输出5行。

SELECT column1 FROM tableName LIMIT 4,5; 从行4(第5行)开始输出5行。

SELECT products.prod_name FROM crashcourse.products;

SELECT * FROM tableName ORDER BY column1; 根据 column1 的值排序查询结果。

SELECT * FROM tableName ORDER BY column1, column2; 根据 column1 排序， 相同项再根据 column2 排序。

SELECT * FROM tableName ORDER BY column1 DESC, column2; column1 降序排序。

SELECT * FROM tableName ORDER BY column1 DESC LIMIT 1; column1 最大的一条。

SELECT * FROM tableName WHERE column1 = "name1"; 限定条件

WHERE 可以使用各种操作符和BETWEEN。
相等是 =。不等 <>, !=。

SELECT * FROM tableName WHERE column2 BETWEEN 10 AND 20; 限定范围

SELECT * FROM tableName WHERE column3 IS NULL; 选择空值

SELECT * FROM tableName WHERE column1="name2" AND column2<10; 多个 WHERE 条件组合。

SELECT * FROM tableName WHERE column1 IN ("name1", "name2", "name3"); WHERE 多个条件的一种简写。

SELECT * FROM tableName WHERE column1 NOT IN ("name1", "name2", "name3"); 非