SQL LCASE函数

这个字符串函数可以在结构化查询语言中显示所有小写字母。它将大写字母或一组大写字母转换为小写字母。

LCASE字符串函数的语法

语法1： 这种语法使用SQL表的列名与LCASE函数一起使用：

SELECT LCASE(Column_Name) AS Alias_Name FROM Table_Name;

在这个语法中，Column_Name是要显示为小写的列的名称。

语法2： 这个语法使用LCASE函数与一组大写字符（字符串）：

SELECT LCASE(String);

语法2： 此语法使用LCASE函数与单个大写字符一起使用：

SELECT LCASE(lower_case_character);

HTML格式的LCASE字符串函数示例

示例1： 以下SELECT查询将以下字符串的所有字符转换为小写（lcase）：

SELECT LCASE(JAVATPOINT IS A GOOD WEBSITE);

输出：

javatpoint is a good website

示例2： 以下SELECT查询无法更改以下字符串的字符，因为LCASE函数无法在SQL中更改字符串的符号和整数。

SELECT LCASE(@#$12453@#);

输出：

@#$12453@#

示例3: 以下SELECT查询将大写字母转换为小写字母：

SELECT LCASE( New Delhi IS the Capital OF India);

输出:

new delhi is the capital of india

示例4: 以下SELECT查询在输出中将字符’S’显示为小写:

SELECT LCASE( S);

输出:

s

示例5：此示例使用LCASE函数与SQL表

在这个示例中，我们将创建一个新表，该表将与LCASE字符串函数一起使用。

在SQL数据库中创建新表的语法如下：

CREATE TABLE table_name
(
1st_Column Data Type (character_size of 1st Column),  
2nd_Column Data Type (character_size of the 2nd column ),  
3rd_Column Data Type (character_size of the 3rd column),  
...  

Nth_Column Data Type (character_size of the Nth column)
);  

以下CREATE语句创建了 Faculty_Info 表：

CREATE TABLE Faculty_Info
(
Faculty_ID INT NOT NULL PRIMARY KEY,  
Faculty_First_Name VARCHAR (100),  
Faculty_Last_Name VARCHAR (100),  
Faculty_Dept_Id INT NOT NULL,
Faculty_Address Varchar(120),
Faculty_City Varchar (80),
Faculty_Salary INT 
);

下面的INSERT查询将大学教师的记录插入到 Faculty_Info 表中：

INSERT INTO Faculty_Info (Faculty_ID, Faculty_First_Name, Faculty_Last_Name Faculty_Dept_Id, Faculty_Address, Faculty_City, Faculty_Salary) VALUES (1001, ARUSH, SHARMA, 4001, AMAN VIHAR, DELHI, 20000);
INSERT INTO Faculty_Info (Faculty_ID, Faculty_First_Name, Faculty_Last_Name Faculty_Dept_Id, Faculty_Address, Faculty_City, Faculty_Salary) VALUES (1002, BULBUL, ROY, 4002, NIRMAN VIHAR, DELHI, 38000 );
INSERT INTO Faculty_Info (Faculty_ID, Faculty_First_Name, Faculty_Last_Name Faculty_Dept_Id, Faculty_Address, Faculty_City, Faculty_Salary) VALUES (1004, SAURABH, SHARMA, 4001, SECTOR 128, MUMBAI, 45000);
INSERT INTO Faculty_Info (Faculty_ID, Faculty_First_Name, Faculty_Last_Name Faculty_Dept_Id, Faculty_Address, Faculty_City, Faculty_Salary) VALUES (1005, SHIVANI, SINGHANIA, 4001, VIVEK VIHAR, KOLKATA, 42000);
INSERT INTO Faculty_Info (Faculty_ID, Faculty_First_Name, Faculty_Last_Name Faculty_Dept_Id, Faculty_Address, Faculty_City, Faculty_Salary) VALUES (1006, AVINASH, SHARMA, 4002, SARVODYA CALONY, DELHI, 28000);
INSERT INTO Faculty_Info (Faculty_ID, Faculty_First_Name, Faculty_Last_Name Faculty_Dept_Id, Faculty_Address, Faculty_City, Faculty_Salary)VALUES (1007, SHYAM, BESAS, 4003, KRISHNA NAGAR, LUCKNOW, 35000);

以下SELECT语句显示了上述 Faculty_Info 表中插入的记录：

SELECT * FROM Faculty_Info; 

以下SELECT查询使用了LCASE函数和上述Faculty_Info表中的Faculty_Last_Name列：

SELECT Faculty_Last_Name, LCASE(Faculty_Last_Name) AS LCASE_LastName FROM Faculty_Info;

这个SQL语句将每个教师的姓氏转换为小写：

输出：

以下SELECT查询在上面的Faculty_Info表中，使用LCASE函数与Faculty_First_Name、Faculty_City和Faculty_Address列，针对faculty_Id大于1002的教职员工。

SELECT Faculty_Id, LCASE(Faculty_First_Name), LCASE(Faculty_Address), LCASE(Faculty_City) FROM Faculty_Info WHERE Faculty_Id >1002;

输出：

以下SELECT查询在上述Faculty_Info表中使用LCASE函数和Faculty_Last_Name和Faculty_Address列的工资大于30000的教职员工：

SELECT Faculty_Id, LCASE(Faculty_Last_Name), Faculty_Dept_Id, LCASE(Faculty_Address), LCASE(Faculty_Salary) FROM Faculty_Info WHERE Faculty_Salary > 30000;

输出：