SQL |通配符运算符

先决条件：SQL | WHERE 条款
在上面提到的文章中讨论了 WHERE 子句，其中还解释了 LIKE运算符，您一定遇到过通配符这个词，现在让我们更深入地了解通配符。

通配符与 LIKE运算符运算符一起使用，有四种基本运算符：

Operator	Description
%	It is used in substitute of zero or more characters.
_	It is used in substitute of one character.
_	It is used to substitute a range of characters.
[range_of_characters]	It is used to fetch matching set or range of characters specified inside the brackets.
[^range_of_characters] or [!range of characters]	It is used to fetch non-matching set or range of characters specified inside the brackets.

基本语法：

SELECT column1,column2 FROM table_name WHERE column LIKE wildcard_operator;
column1 , column2: fields in the table
table_name: name of table
column: name of field used for filtering data

查询

• 从学生表中获取名称以字母“T”结尾的记录。

  SELECT * FROM Student WHERE NAME LIKE '%T';
  

  输出：

  ROLL_NO	NAME	ADDRESS	PHONE	Age
  3	SUJIT	ROHTAK	XXXXXXXXXX	20
  3	SUJIT	ROHTAK	XXXXXXXXXX	20

• 从学生表中获取名称以任何字母结尾但从“RAMES”开始的记录。

  SELECT * FROM Student WHERE NAME LIKE 'RAMES_';
  

  输出：

  2RAMESHGURGAONXXXXXXXXXX18

  ROLL_NO	NAME	ADDRESS	PHONE	Age
  2	RAMESH	GURGAON	XXXXXXXXXX	18

• 从学生表中获取地址包含字母“a”、“b”或“c”的记录。

  SELECT * FROM Student WHERE ADDRESS LIKE '%[A-C]%';
  

  输出：

  2RAMESHGURGAONXXXXXXXXXX18

  ROLL_NO	NAME	ADDRESS	PHONE	Age
  2	RAMESH	GURGAON	XXXXXXXXXX	18
  2	RAMESH	GURGAON	XXXXXXXXXX	18
  3	SUJIT	ROHTAK	XXXXXXXXXX	20
  3	SUJIT	ROHTAK	XXXXXXXXXX	20

• 从学生表中获取不包含字母“a”、“b”或“c”的 ADDRESS 记录。

  SELECT * FROM Student WHERE ADDRESS LIKE '%[^A-C]%';
  

  输出：

  ROLL_NO	NAME	ADDRESS	PHONE	Age
  1	Ram	Delhi	XXXXXXXXXX	18
  4	SURESH	Delhi	XXXXXXXXXX	18

• 从学生表中获取记录，PHONE 字段的第 1 个位置为“9”，第 4 个位置为“5”。

  SELECT * FROM Student WHERE PHONE LIKE '9__5%';
  

  输出：

  ROLL_NO	NAME	ADDRESS	PHONE	Age
  1	Ram	Delhi	XXXXXXXXXX	18

• 从 Student 表中获取包含总共 6 个字符的ADDRESS 的记录。

  SELECT * FROM Student WHERE ADDRESS LIKE '______';
  

  输出：

  ROLL_NO	NAME	ADDRESS	PHONE	Age
  3	SUJIT	ROHTAK	XXXXXXXXXX	20
  3	SUJIT	ROHTAK	XXXXXXXXXX	20

• 从Student表中任意位置获取包含’OH’的ADDRESS记录，并且结果集不应包含重复数据。

  SELECT DISTINCT * FROM Student WHERE ADDRESS LIKE '%OH%';
  

  输出：

  ROLL_NO	NAME	ADDRESS	PHONE	Age
  3	SUJIT	ROHTAK	XXXXXXXXXX	20