MYSQL中的JOIN

CREATE TABLE testa(
aid INT NOT NULL,
anumber INT NOT NULL,
PRIMARY KEY(aid)
);
INSERT INTO testa (aid,anumber)VALUES(1,12123);
INSERT INTO testa (aid,anumber)VALUES(2,22123);
INSERT INTO testa (aid,anumber)VALUES(3,32123);
INSERT INTO testa (aid,anumber)VALUES(4,12123);

CREATE TABLE testb(
bid INT NOT NULL,
bnumber INT NOT NULL,
PRIMARY KEY(bid)
);
INSERT INTO testb (bid,bnumber)VALUES(1,12123);
INSERT INTO testb (bid,bnumber)VALUES(2,22123);
INSERT INTO testb (bid,bnumber)VALUES(3,32123);
INSERT INTO testb (bid,bnumber)VALUES(6,12123);