USE AdventureWorks2022; GO CREATE VIEW Person.AddrState WITH SCHEMABINDING AS SELECT a.AddressID, a.AddressLine1, s.StateProvinceCode, s.CountryRegionCode FROM Person.Address a WITH (NOLOCK), Person.StateProvinc
partitions:NULL type:ALL possible_keys: idx_create_time key:NULL key_len:NULL ref:NULL rows:407632 filtered:5.00 Extra:Using where 1rowinset,1 warning (0.00 sec) 查询字段有索引,但是索引失效 KEY`idx_create_time`(`create_time`), status 字段的区分度 mysql> selectstatus,count(*) from ...
MAX() and MIN() in Nested SELECT As we know, theMAX()function returns the maximum value. Similarly, theMIN()function returns the minimum value. However, if we want to select the whole row containing that value, we can use the nestedSELECTstatement like this. -- MIN() function in a n...
select * from t1 join t2 on t.double_value = cast(t2.string_value as double); window.ref.prev.window.alias 说明:Window Function引用同级select List中的其他Window Function Alias的问题。 示例 如果rn在t1中不存在,错误写法如下。 select row_number() over (partition by c1 order by c1) rn, ...
如果查询部分有对视图的SELECT直接引用,则索引视图将保持精简。 如果指定或WITH (NOEXPAND)指定WITH (NOEXPAND, INDEX( <index_value> [ , *...n* ] ) ),视图也会保持精简状态。 有关查询提示NOEXPAND的详细信息,请参阅使用 NOEXPAND。 该提示仅影响语句SELECT部分中的视图,包括这些视图,INSERTUPDATEMERGE以及...
第二步就是语法分析,语法分析会对SQL做一些语法检查,比如单引号有没有闭合等, 然后根据MySQL定义的语法规则,根据SQL语句生成一个数据结构。这个数据结构我们把它叫做解析树(select_lex)。 举个栗子: 词法语法分析是一个非常基础的功能,Java的编译器、百度搜索引擎如果要识别语句,必须也要有词法语法分析功能。 任何数...
SELECT 语句 SELECT[predicate]{*|table.*|[table.]field [,[table.]field2[,...]]} [AS alias1 [,alias2[,...]]] FROM tableexpression [,...][IN externaldatabase] [WHERE...] [GROUP BY...] [HAVING...] [ORDER BY...] [WITH OWNERACCESS OPTION] ...
SELECT BusinessEntityID, VacationHours FROM HumanResources.Employee WHERE BusinessEntityID = 4; -- This statement, which caused the snapshot transaction -- to fail, will succeed with read-committed using row versioning. UPDATE HumanResources.Employee SET SickLeaveHours = SickLeaveHours -...
URL: http://dev.mysql.com/doc/refman/8.0/en/select.html mysql> 2>.测试数据准备 建表语句如下: mysql>CREATEDATABASEyinzhengjieDEFAULTCHARACTERSET=utf8; Query OK,1row affected,1warning (0.00sec) mysql>mysql>USEyinzhengjieDatabasechanged
col_name,...)]ON((col_value,col_value,...),(col_value,col_value,...),...)[STOREDASDIRECTORIES][[ROWFORMATrow_format][STOREDASfile_format]|STOREDBY'storage.handler.class.name'[WITHSERDEPROPERTIES(...)]][LOCATIONhdfs_path][TBLPROPERTIES(property_name=property_value,...)][ASselect_...