The difference between a left join, right join, INNER join

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

[[email protected]]Sql>Select *  fromA; number name---- ---------- +Zhang San -John Doe theHarry[[email protected]]Sql>Select *  fromb; Numbered Items---- ---------- +TV -Video Recorder4000Bicycle[[email protected]]Sql>Set NULLNull value--in order to display the aspect, I define NULL as [null value][[email protected]]Sql>SelectA.*B.*  fromAInner JoinB onA. Number=B. number; number Name number product---- ---------- ---- ---------- +Tom +TV -John doe -Video Recorder[[email protected]]Sql>SelectA.*B.*  fromA Left JoinB onA. Number=B. number; number Name number product---- ---------- ---- ---------- +Tom +TV -John doe -Video Recorder theWang value NULL[[email protected]]Sql>SelectA.*B.*  fromA Right JoinB onA. Number=B. number; number Name number product---- ---------- ---- ---------- +Tom +TV -John doe -VCR null value NULL value4000Bicycle[[email protected]]Sql>SelectA.*B.*  fromA Full JoinB onA. Number=B. number; number Name number product---- ---------- ---- ---------- +Tom +TV -John doe -Video Recorder theWang value NULL null value NULL value4000Bike

The difference between a left join, right join, INNER join