sql compare two tables for differences

. Partial SQL Statement Differences(1) Sql:select top * FROM tableOra:select * FROM table where rownum(2) Sql:select * from T1 join T2 on T1.C1=T2.C1Ora:select * from T1,t2 where t1.c1=t2.c1(3) SELECT * from T1 LEFT join T2 on T1.C1=T2.C1Ora:select * from T1,t2 where T1.C1=T2.C1 (+)(4) Sql:select * from T1 right join T2 on T1.C1=T2.C1Ora:select * from T1,t2 where T1.C1 (+) =T2.C12. Other technical differenc

extension.The space page is dedicated to the allocation and management of data spaces, including: PFS pages (page free space): Record whether a page is assigned, in a mixed or consistent extension, and how much space is available on the page; Gam page (Global allocation MAP) and Sgam page (secodary Global allocation map): Used to record the location of an idle extension or a mixed extension containing free pages. Sqls Comprehensive utilization of these three types of paging files creates a new

an entire table or partition, such as the following: INSERT OVERWRITE TABLE T1 SELECT * from T2; • Use the LOAD statement to insert new data.5. Hive does not support insert into table values (), update,delete operationBecause data is stored in HDFs, these operations are not supported, and hive does not require a sophisticated locking mechanism to read and write data.6. Hive supports embedding a mapreduce program to handle complex logicFor example From ( MAP doctext USING ' Python wc_mapper.py '

varchar (max) After the problem, because varchar (max) in the Behavior and varchar (n) The same, so can be used in Varcahr can be used in the varchar (max OnIn addition, this also supports the use of AFTER triggers on column references to large-value data types in the inserted and deleted tables. Text will not work, in short, with a large value data type, I am "waist also does not ache, leg also not sour, breath can also on six floor." What are you w

incompatible in the equal to operator. Query two: SELECT [text], [Varcharmax]from [TestDB]. [dbo]. [Asdf]where [Varcharmax] = ' 1111111 ' can run successfully in Ms SQL2005 and above, add a large value data type (varchar (max), nvarchar (max), varbinary ( Max)). A large value data type can store up to 2^30-1 bytes of data. These data types behave in the same way as the smaller data types varchar, nvarchar, and varbinary. MicrosoftThis data type is used instead of the previous text, ntext, and

* from B WHERE a.id = b.aid) Execution result is 3 A3 N Bsp SQL in differs from exists in to determine whether a given value matches a value in a subquery or list. EXISTS Specifies a subquery that detects the existence of a row. Compare queries using EXISTS and in This example compares two semantically similar queries. The first query uses EXISTS and the second query uses in. Note Two queries ret

(unixtime)). Isoweekday ()print '/t ' join ([UserID, MovieID, rating, STR (weekday)]) VI. Using the mapping script //CREATE TABLE, split the field values in rows by the delimiter create TABLE u_data_new ( userid INT, movieid int, rating int, weekday INT) row FORMAT delimited fields TERMINATED by '/t '; //loading python files into system add FILE weekday_mapper.py; Seven, the data by the week segmentationINSERT OVERWRITE TABLE u_data_newSELECTTRANSFORM (userid, MovieID, ra

Tags: left joins right join INNER JOINLeft join returns records that include all the records in the left table and the equivalent of the junction fields in the right tableRight join returns records that include all records in the right table and the junction fields in the left tableINNER JOIN (equivalent join) returns only rows that have the same join field in two tables Examples are as follows:--------------------------------------------Table A recor

Label:In the original: SQL gets the last generated identity value ident_current, @ @IDENTITY, scope_identity usage and differencesIdent_currentReturns the last identity value generated for the specified table in any session and any scope.GrammarIdent_current('table_name')Parameterstable_nameis the name of the table whose identity value will be returned. The data type of table_name is varcharand has no default value.return typesql_variantCommentsIdent_

watermark (back to the original).4. Efficiency: Drop > Truncate > Delete5. Security: Careful use of drop and truncate, especially when there is no backup, want to delete some data can use delete need to take WHERE clause, rollback segment is big enough, want to delete table can use drop, want to keep table just want to delete all the data of the table, If you have nothing to do with things you can use truncate, if it is related to things, or want to trigger trigger, or delete, if it is to tidy

Label:In simple terms, the difference between update and alter, such as Right-click Properties Update Everymatchinfo SET matchno=111--Updating permissions ALTER TABLE EVERYMATCHINFO add IDD INT--Change permissions The actual is the difference between DDL and DML, with some brief instructions DML (Data Manipulation language) is the language of the manipulation: they are select, UPDATE, INSERT, DELETE, just like its name, these 4 commands are the languages used to manipulate the data in the da

followsAid Anum Bid Bname1 20050111 1 20060324012 20050112 2 20060324023 20050113 3 20060324034 20050114 4 2006032404NULL NULL 8 2006032408Summary: The table before 1:join is arranged in front, the table after join is behind;2: Leftist is based on the data, right-hand is to the right of the data to prevail;3 : Inner Join as followsSELECT * FROM t_a inner join t_b on t_a.aid = T_b.bidShown below:Aid Anum Bid bname1 20050111 1 20060324012 20050112 2 20060324023 20050113 3 20060324034 20050114 4 2

First of all, the primary key is also called the PRIMARY KEY constraint, which is also a constraint, look at it and the creation syntax of the UNIQUE constraint: ALTER TABLE person add constraint pk_id primary key (ID) ALTER TABLE person add constraint uq_name unique (Name) Both primary keys and unique constraints require field values to be unique, except in addition to the following differences: • The same table can have only one primary key

reserved, false deletes the row, and finally returns the result set.Differentiation and application ScenariosIn and exists differences: if the subquery results in a smaller number of result sets, the table in the main query should use in if it is large and indexed, whereas if the outer main query records are smaller, the tables in the subquery are large and the indexes are indexed with exists. In fact, we