If I suppose that one employee can belong to severan departments, Sir ,please write article on MySQL ans PostgreSQL Such as performance ans which one is better to follow ect WHY MY SQL SHOW ONLY COLUMN AND IT DOESN'T SHOW ROW IN TABLE? (SELECT p.`Code`, c.Name, a.Name, p.`Name`, p.`Price`, p.`Description`,p.`ImageName`, p.`Date` FROM `products` p JOIN `categories` c ON p.CID = c.ID JOIN `accessories` a ON p.AID = a.ID) Oracle, SQLServer 2008 and SQL Server 2010 please Can you also share some JOIN examples from other major database e.g. This particular example of How to join three tables in SQL made my life easy. dept_id įrom long time I had difficulty joining more than two tables, as soon as number of tables increased from 2 to 3, it's started getting messy for me. In short, this is one of the most important topics in SQL both from experience and interview points of view. SQL Join is also a very popular topic in SQL interviews and there are always been some questions from Joins, like the difference between INNER and OUTER JOIN, SQL query with JOIN like Employee Department relationship and Difference between LEFT and RIGHT OUTER JOIN, etc. ![]() I have found that understanding table relationships as the primary key and foreign key helps to alleviate confusion than the classical matching row paradigm. As I said it can be extremely confusing to understand the join of three or more tables. If you look it closely you find that table 2 is a joining table that contains the primary key from both table 1 and table 2. In the case of joining three tables table, 1 relates to table 2 and then table 2 relates to table 3. Most of the time we only join two tables like Employee and Department but sometimes you may require joining more than two tables and a popular case is joining three tables in SQL.
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