我怎麼能忽略大小寫的區別與MySQL

Question

搜索時，我怎麼能忽略大小寫的區別與MySQL搜索

Answer 1

做這樣的事情的時候：

SELECT user 
FROM users 
WHERE UPPER(user) = UPPER('moustafa'); 

基本上您將結果轉換爲一種情況，並將其與轉換爲大寫的搜索詞進行比較，從而有效地忽略大小寫。

Answer 2

通常，您應該使用WHERE UPPER（COLUMNNAME）= UPPER（'valuetocompare'）。

或者，您culd使用WHERE UPPER（COLUMNNAME）像UPPER（「％valuetocompare％」），如果你想要做一個字符串搜索

Answer 3

您可以存儲在MySQL中的數據更低的情況下，只是進行查詢在上面。

Answer 4

可以使用UPPER和LOWER函數，但也可以通過選擇適當的歸類和/或列類型來影響區分大小寫。

例如，latin1_general_cs是區分大小寫既VARCHAR和VARBINARY：

DROP TABLE IF EXISTS `case_sensitive`; 
CREATE TABLE `case_sensitive` (
    `id` INT NOT NULL AUTO_INCREMENT, 
    `nonbinary` VARCHAR(255), 
    `binary` VARBINARY(255), 
    PRIMARY KEY (`id`) 
) ENGINE=InnoDB COLLATE latin1_general_cs; 

INSERT INTO `case_sensitive` (`nonbinary`, `binary`) VALUES ('A', 'A'); 

SELECT * FROM `case_sensitive` WHERE `nonbinary` = 'A'; 

+----+-----------+--------+ 
| id | nonbinary | binary | 
+----+-----------+--------+ 
| 1 | A   | A  | 
+----+-----------+--------+ 
1 row in set (0.00 sec) 

SELECT * FROM `case_sensitive` WHERE `binary` = 'A'; 

+----+-----------+--------+ 
| id | nonbinary | binary | 
+----+-----------+--------+ 
| 1 | A   | A  | 
+----+-----------+--------+ 
1 row in set (0.00 sec) 

SELECT * FROM `case_sensitive` WHERE `nonbinary` = 'a'; 

Empty set (0.00 sec) 

SELECT * FROM `case_sensitive` WHERE `binary` = 'a'; 

Empty set (0.00 sec) 

而latin1_general_ci不區分大小寫與VARCHAR，並區分大小寫與VARBINARY：

DROP TABLE IF EXISTS `case_insensitive`; 
CREATE TABLE `case_insensitive` (
    `id` INT NOT NULL AUTO_INCREMENT, 
    `nonbinary` VARCHAR(255), 
    `binary` VARBINARY(255), 
    PRIMARY KEY (`id`) 
) ENGINE=InnoDB COLLATE latin1_general_ci; 

INSERT INTO `case_insensitive` (`nonbinary`, `binary`) VALUES ('A', 'A'); 

SELECT * FROM `case_insensitive` WHERE `nonbinary` = 'A'; 

+----+-----------+--------+ 
| id | nonbinary | binary | 
+----+-----------+--------+ 
| 1 | A   | A  | 
+----+-----------+--------+ 
1 row in set (0.00 sec) 

SELECT * FROM `case_insensitive` WHERE `binary` = 'A'; 

+----+-----------+--------+ 
| id | nonbinary | binary | 
+----+-----------+--------+ 
| 1 | A   | A  | 
+----+-----------+--------+ 

SELECT * FROM `case_insensitive` WHERE `nonbinary` = 'a'; 

+----+-----------+--------+ 
| id | nonbinary | binary | 
+----+-----------+--------+ 
| 1 | A   | A  | 
+----+-----------+--------+ 

SELECT * FROM `case_insensitive` WHERE `binary` = 'a'; 

Empty set (0.00 sec) 

你應該因此請選擇最適合您需求的整理和列類型。你可以在這裏找到更多的信息：

區分大小寫的字符串搜索
http://dev.mysql.com/doc/refman/5.1/en/case-sensitivity.html

字符集和校對MySQL中
http://dev.mysql.com/doc/refman/5.1/en/charset-mysql.html

字符集和校對，MySQL的支持
http://dev.mysql.com/doc/refman/5.1/en/charset-charsets.html

Answer 5

我在你搜索的列上使用utf8_unicode_（CI）不區分大小寫的排序....和它的工作原理

Answer 6

SELECT * FROM table_name WHERE column_name1 LIKE '%A%' OR column_name1 LIKE '%a%';