difference between inner join and outer join

is not based on who, it only shows records that match the criteria.--------------------------------------------Note:The left JOIN operation is used to combine records from the source table in any from clause. Use the left JOIN operation to create an outer join of the side. The left

that inner join is not based on who, it only shows records that match the criteria.--------------------------------------------Note:The left JOIN operation is used to combine records from the source table in any from clause. Use the left JOIN operation to create an outer

1. Theory As long as the public fields of the two tables have matched values, the records in the two tables are combined. My personal understanding: Use a common field to calculate the intersection of the two tables that meet the requirements, and combine the records that meet the requirements of each table with the common fields. Syntax From Table1 inner join Table2 on Table1. field1 compopr Table2

1. Theory As long as the public fields of the two tables have matched values, the records in the two tables are combined. My personal understanding: Use a common field to calculate the intersection of the two tables that meet the requirements, and combine the records that meet the requirements of each table with the common fields. Syntax From Table1 inner join Table2 on Table1. field1 compopr Table2

Tags: connecting left connection Ali data sheet full join left and right out combination case connections in SQL can be divided into inner joins, outer joins, and cross connections. 1. Cross join Without a WHERE clause, it will return the Cartesian product of the two tables connected, and the number of rows returning

coproduct e--PK = COMPANYCD, productsalescd on B.COMPANYCD = E.COMPANYCD and B.PRODUCTSALESCD = E.productsalescd LEFT Join Couom i--PK = uomid on h.uomid = I.uomid INNER JOIN coproductoldinformation J--PK = C OMPANYCD, Bfstatus, speccd on A.COMPANYCD = J.COMPANYCD and B.bfstatus = j.bfstatus and B.PRODUCTSALESCD = J.ProductS ALESCD

bname1 a20050111 1 20060324012 a20050112 2 20060324023 a20050113 3 20060324034 a20050114 4 2006032404Null null 8 2006032408(The number of affected rows is 5) Result description:After careful observation, we will find that the result of left join is exactly the opposite. This time, it is based on the right table (B) and is filled with null when table A is insufficient. 3. Inner joinThe SQL statement is a

Left join returns records that include all records in the left table and join fields in the right table.Right join returns records that include all records in the right table and the joined fields in the left table.Inner join (equivalent join) returns only rows with equal

NULL NULL NULLB524. Fully connected1 Select * fromT1 Full outer JoinT2 onT1. B=t2.b2 3 A b C B E4 ---------- ---------- ---- ---------- ----5A1 B15B136A1 B26B277A2 B38B3Ten8A2 B38B329A2 B4 A NULL NULLTen NULL NULL NULLB525. Cross connection (Cartesian product)1 Select * fromT1 Cross JoinT22 3 A b C B E4 ---------- ---------- ---- ---------- ----5A1 B15B136A1 B15B277A1 B15B3Ten8A1 B15B329A1 B15B52TenA1 B26B13 OneA1 B26B2

081219 -- Retrieve the public part Select * From t_goods a inner join t_storein BOnA.Gid = B.GID -- All the tables on the right are retrieved, and the tables on the left are matched. Select * From t_goods a right join t_storein BOnA.Gid = B.GID -- Retrieve all tables on the left and matched tables on the right Select * From t_goods a left

Inner join on, left join on, right join on, innerjoin 1. Definition: Inner join: only records with equal join fields in two tables are returned. Left

left join is exactly the opposite, this time it is based on the right table (B), where a table is not enough to fill with null. 4. Inner Join Example: 4.1Select * from A inner join B on a.aid = B.bid; This shows only the records of A.aid = B.bid. This shows that