如何在MySQL中检查多个列中的单个值?
您可以借助IN运算符检查多个列中的一个值。语法如下-
select *from yourTableName where value IN(yourColumnName1, yourColumnName2,......N);
为了理解上述概念,让我们创建一个包含一些列的表。创建表的查询如下-
mysql> create table OneValueFromAllColumns−> (
−> StudentId int,
−> StudentFirstname varchar(200),
−> StudentLastname varchar(200),
−> StudentAge int
−> );
借助select语句在表中插入一些记录。查询如下-
mysql> insert into OneValueFromAllColumns values(1,'John','Smith',23);mysql> insert into OneValueFromAllColumns values(2,'Carol','Taylor',22);
mysql> insert into OneValueFromAllColumns values(3,'Maria','Garcia',19);
mysql> insert into OneValueFromAllColumns values(4,'Bob','Wilson',21);
显示我们在上方插入的所有记录。显示表中所有记录的查询如下-
mysql> select *from OneValueFromAllColumns;
以下是输出-
+-----------+------------------+-----------------+------------+| StudentId | StudentFirstname | StudentLastname | StudentAge |
+-----------+------------------+-----------------+------------+
| 1 | John | Smith | 23 |
| 2 | Carol | Taylor | 22 |
| 3 | Maria | Garcia | 19 |
| 4 | Bob | Wilson | 21 |
+-----------+------------------+-----------------+------------+
4 rows in set (0.00 sec)
这是检查多个列中单个值的查询。我们正在多个列(即StudentId,StudentFirstname,StudentLastname和StudentAge)中检查值“ Taylor”。
查询如下-
mysql> select *from OneValueFromAllColumns where 'Taylor' IN(StudentId,StudentFirstname,StudentLastname,StudentAge);
以下是显示值为“ Taylor”的记录的输出-
+-----------+------------------+-----------------+------------+| StudentId | StudentFirstname | StudentLastname | StudentAge |
+-----------+------------------+-----------------+------------+
| 2 | Carol | Taylor | 22 |
+-----------+------------------+-----------------+------------+
1 row in set, 4 warnings (0.03 sec)
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