select from two tables sql without join

Label: INNER JOIN (equivalent join) returns only rows that have the same join field in two tables Left join returns records that include all the records in the left table and the equivalent of the junction fields in the right table Right

Label: Inner JOIN (equivalent connection) returns only rows that have the same join field in two tables Left join returns records containing all the records in the left table and the equivalent of the junction fields in the right table Right join returns records that contain

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

I. Concepts 1. Cross join)Without the WHERE clause, it returns the Cartesian product of the two joined tables, and the number of rows returned is equal to the product of the number of rows in the two tables.For example:A: select a. *, B. * From Table1 A, Table2 B where a. ID = B. IDB: Select * From Table1 a cross

some elements are in a, not in B, and vice versa. Set " A" set "B" AA BB -------- -------- Item 1 Item 3 Item 2 Item 4 Item 3 Item 5 Item 4 Item 6 Left OUTER JOINNow execute the following SQL statement (left connection, OUTER join): SELECT * from A left OUTER

(primary table) and the SAL (schedule) information related to EMP. Right connect [SQL] view plain copy Select * from EMP right join SAL on EMP. ename = SAL.ename; Right connection, table Sal is the primary table, so the query results show all the information of the salt (the primary table) and the EMP (schedule) and the information that Sa

Label:Transferred from: http://blog.csdn.net/jz20110918/article/details/41806611 Let's say we have two tables. Table A is the sheet on the left. Table B is the list on the right. Each of them has four records, of which two records name is the same, as follows: Let's look at the different joins Table A Id Name 1 Pirate 2 Monkey 3 Ninja

In the relational database management system, the relationship between data does not have to be determined when a table is created, and all information about an object is often stored in a table. When retrieving data, you can use the join operation to query information about different entities in multiple tables. Connection operations bring great flexibility to users. They can add new data types at any time

Connection property. If the value is mapped to I by a hash function, then the tuple of relation s must be in H (RI), and the tuple of the relationship s must be in H (SI). Therefore, the tuples in H (RI) need to be compared with the tuples in H (SI) and not necessarily with any other partitions of S. It is obvious that this algorithm is much less expensive than the above algorithm. as two tables are partitioned, the benefit is that you can use para

information of the EMP (primary table) and the SAL (schedule) information related to EMP. Right-connect the Select * from emp to ' join SAL on EMP '. ename = SAL.ename; Right connection, table Sal is the primary table, so the query results show all the information of the salt (the primary table) and the EMP (schedule) and the information that Sal wants to close.