SELECT*,(SELECTcount(*)FROMstudentWHEREcid=classes.id)ASnumFROMclassesORDERBYnum; 2.2 in、not in 子句查询示例 查询班级 id 大于小于的这些班级的学生信息 SELECT*FROMstudentWHEREcidIN(SELECTidFROMclassesWHEREid>2andid<4); 查询不是班的学生信息 SELECT*FROMstudentWHEREcidNOTIN(SELECTidFROMclassesWHEREna...
Convert between ASCII or UNICODE code to a string character. SELECT CHAR(65) 'A' Numeric integer value as input. CHARINDEX and PATINDEX Find the starting position of one string expression or string pattern within another string expression. SELECT CHARINDEX...
SET @LastName = 'mc donald' -- Test value -- Find space in name:
--显示字符串"China"中每个字符的ASCII值和字符 declare@positionint,@stringchar(8) set@position=1 set@string='China' while@position<=datalength(@string) begin selectASCII(substring(@string,@position,1)),char(ASCII(substring(@string,@position,1))) set@position=@position+1 end go --检查学生的...
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REPLACE ( 'string_expression1' , 'string_expression2' , 'string_expression3' )--用第三个表达式替换第一个字符串表达式中出现的所有第二个给定字符串表达式。 STUFF ( character_expression , start , length , character_expression )--删除指定长度的字符并在指定的起始点插入另一组字符。
Example 9: Use T-SQL Regex to Find Text Rows that Contain a Number We can find a row that contains the number as well in the text. For example, we want to filter the results with rows that contain number 0 to 9 in the beginning. ...
Also you can find the unique index that SQL Server uses to enforce a primary key constraint by querying sys.indexes. For example, the following query shows the unique index declared on the Production.Categories table for the PK_Categories primary key constraint. ...
--not in 不在其中 select • ect * from student where id not in (1, 2); --is null 是空 select • ect * from student where age is null; --is not null 不为空 select • ect * from student where age is not null;
text Variable-length non-Unicode data in the code page of the server and with a maximum string length of 2^31 - 1 (2,147,483,647). When the server code page uses double-byte characters, the storage is still 2,147,483,647 bytes. Depending on the character string, the storage size ...