25 March 20249 min read T-SQL Programming Edward PollackinT-SQL Programming Find and Replace Text in Strings in T-SQL String manipulation is an inevitable task for developers and data professionals alike. Despite all the best efforts to normalize databases,... ...
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(SELECTidFROMclassesWHERE...
SET @SQLString = @SQLString + ' Longitude>='+CAST(@RectLeftParam AS varchar(10)) SET @SQLString = @SQLString + ' AND Longitude<=' + CAST(@RectRightParam AS varchar(10)) SET @SQLString = @SQLString + ' AND Latitude>=' + CAST(@RectBottomParam AS varchar(10)) SET @SQLString =...
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...
SELECT*FROMstudentWHEREcidIN(SELECTidFROMclassesWHEREid>2andid<4); 查询不是班的学生信息 SELECT*FROMstudentWHEREcidNOTIN(SELECTidFROMclassesWHEREname='2班') IN、NOT IN 后面的子句返回的结果必须是一列,这一列的结果将会作为查询条件对应前面的条件。如 cid 对应子句的 id。
sql_low_priority_updates sql_log_off sql_log_update sql_select_limit sql_small_result sql_big_result sql_warnings straight_join starting status string table tables temporary terminated text then time timestamp tinyblob tinytext tinyint trailing to...
Indexes facilitate quicker database searching. The SQL Server must scan the entire table and check every single row to find matches if a column in the WHERE stipulation has no index. This may slow down operations in large data sets. Indexes are used to locate all rows that match a specific...
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. ...
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. ...
--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;