difference between inner join and outer join

Differences between inner join, left JOIN, right join, outer join in SQLFor example, you'll know!Table A (A1,B1,C1) b (A2,B2)A1 B1 C1 A2 B201 Mathematics 95 01 Sheets Three02 Language 90 02 John Doe English Harry Select A.*, b.* f

tables) horizontally, and produce a new result set by combining rows from one data source with rows that match it into a single new tuple.SQL provides several types of connection methods, the difference being that the method used to select the rows to connect from each overlapping set of data is different.Connection type definitionAn inner join connects only mat

This connection is often used in early query statements, which is a small problem. Therefore, I checked the information and summarized it as follows: External connections are easier to understand,A. It is generally used in some classification codes. For example, if you have an employee information table, the position information isCodeAnd the meaning of this Code is described in the position table.B. Classified information storage. For example, in the preceding employee information table, the

=b.statuscode and that is, there is a where condition control, and on can be followed by multiple conditions,the query results are the same as the first one.3. Right Join,right outer JOINRight join is called to connect, the right outer join is called an

Various joins in MySQL 1. Cartesian Product (cross join) In MySQL, you can think of cross join or omit cross as join, or use ',' For example Select * From Table1 cross join Table2 Select * From Table1 join Table2 Select * From Table1, Table2 Because the returned result is

Tags: www. POS nbsp Join table data Intersection case tagThe difference between inner join, outer join, and Cross join in SQL many people do not know, I also ask, just look for informat

Tags: table cartesian outer data str name OSS PHP altBy default, the inner join, the left join and the right join used in development belong to the outer join, and the

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Reprint Address: http://www.phpddt.com/db/inner_join-outer-join.html respect for the work of others is to respect their own achievements!The difference between inner join, outer join, and Cross

Label:The difference between inner join, outer join, and Cross join in SQL many people do not know, I also ask, just look for information to look at, with their previous understanding, if you use

Tags: share where select HTTP filter png same PHP outBy default, the inner join, the left join and the right join used in development belong to the outer join, and the outer

table 1 alias a left join Table 2 alias B in alias a. Column 1 equals alias B. Column 1 where alias a. Column 4 = 1 and alias a. Column 5 = 1 7.4. Left join 7.3.1 synchronize data from two tables Program codeUpdate ctarticle a inner join cttag B ON a. articleid = B. articleid SET B. classid = a. classid, B. nclassid =

Adate1 A12 A23 A3Table BBid Bdate1 B12 B24 B4Two tables A, B connected, to remove fields with the same IDSELECT * from a INNER join B on a.aid = B.bid This is only the matching data is taken out.At this point, the removal is:1 A1 B12 A2 B2Then the left join means:SELECT * from a LEFT join B on a.aid = B.bidFirst remov

1. A. Union select Column1, column2 from table1 Union select Column1, column2 from Table2 B. Intersection join SELECT * FROM table 1 as a JOIN table2 B on A.name=b.name c. No in SELECT * "from table1 WHERE name does not" (SELECT name from table2) d. Cartesian product The SELECT * FROM table1 CROSS JOIN table2 is the same as the select * from Table1,table2 2. The

For example: Table A have 12 (8 + 4) entries, 8 entries have valid relation with BTable B have 80 (77 + 3) entries, 77 entries have valid relation with. Then the return amount of join is:Cross join: 12*80Inner join: 77Full outer join: 77 + 4 + 3Left

first, data constructionFirst build the table, then talk.Create DatabaseTest UseTestCreate TableA (AIDint Identity(1,1)Primary Key, namenvarchar( -), ageint)Create TableB (BIDint Identity(1,1)Primary Key, namenvarchar( -), Genderint)After creation, insert dataInsertA (Name,age)Values('Zhang San', *)InsertA (Name,age)Values('John Doe', -)InsertA (Name,age)Values('XXX', *)InsertA (Name,age)Values('YYY', *)InsertB (Name,gender)Values('Zhang San',1)InsertB (Name,gender)Values('John Doe',1)InsertB (N

* / Select A.*, B.* from aleftjoin b on = b.a_id;A right outer join (either a outer join): A reverse join of a left outer join. All rows of the right table will be returned. If a ro

Tags: load http Select detail LAN margin src lin bleExcerpt from: http://blog.csdn.net/scythe666/article/details/51881235 By default, the inner join, the left join and the right join used in development belong to the outer join, a

TABLE EMPModify ename NOT null; --drop NOT NULL ContraintALTER TABLE EMPModify ENAME null;--drop constraintALTER TABLE EMPDrop constraint unique (name);ALTER TABLE EMPDrop constraint Fk_emp_deptno;--Disabling constraintsALTER TABLE EMPDisable constraint Fk_emp_deptno;--Enable constraintsALTER TABLE EMPEnable constraint Fk_emp_deptno;--oracle connection divided into inner join (

An introduction to the differences between inner join, outer join, and Cross join in SQL:There are two tables, table A is the one on the left. Table B is the list on the right. Each of them has four records, of which two records have the same name:The result of the 1.