sql_CONCAT拼接SUBSTR截取
CONCAT和SUBSTR不同的数据库有不同的语法。
（1）CONCAT
MySQL: CONCAT( )
Oracle: CONCAT( ), ||
SQL Server: +
（2）SUBSTR
MySQL: SUBSTR( ), SUBSTRING( )
Oracle: SUBSTR( )
SQL Server: SUBSTRING( )
（3）具体用法如例：
SELECT CONCAT (Region_Name, Store_Name) FROM Geography WHERE Store_Name = Boston;
查询结果：EastBoston
SELECT Region_Name || || Store_Name FROM Geography WHERE Store_Name = Boston;
查询结果：East Boston
SELECT Region_Name + + Store_Name FROM Geography WHERE Store_Name = Boston;
查询结果：East Boston
SELECT SUBSTR (Store_Name, 3) FROM Geography WHERE Store_Name = Los Angeles;
查询结果：s Angeles
SELECT SUBSTR (Store_Name, 2, 4) FROM Geography WHERE Store_Name = San Diego;
查询结果：an D
CONCAT和SUBSTR不同的数据库有不同的语法。 （1）CONCAT MySQL: CONCAT( ) Oracle: CONCAT( ), || SQL Server: + （2）SUBSTR MySQL: SUBSTR( ), SUBSTRING( ) Oracle: SUBSTR( ) SQL Server: SUBSTRING( ) （3）具体用法如例： SELECT CONCAT (Region_Name, Store_Name) FROM Geography WHERE Store_Name = Boston; 查询结果：EastBoston SELECT Region_Name || || Store_Name FROM Geography WHERE Store_Name = Boston; 查询结果：East Boston SELECT Region_Name + + Store_Name FROM Geography WHERE Store_Name = Boston; 查询结果：East Boston SELECT SUBSTR (Store_Name, 3) FROM Geography WHERE Store_Name = Los Angeles; 查询结果：s Angeles SELECT SUBSTR (Store_Name, 2, 4) FROM Geography WHERE Store_Name = San Diego; 查询结果：an D
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