Problem in using joins on table

Question

hey.. i have two tables having three same columns.. so when i m using join on them its not returning me any output.. is it is necessary only to have a single matching column??? plz help..........

Suthish Nair · Answer

Akash, my advice is that you need to read and work on more about SQL Joins before moving further.

Syed Nayab Ali · Answer

Hi Alec it is not necessary to make join only on one column. Multiple column can be use in join, it will help you to filter data more specificly. Try to use following syntax to get result Select a.column1, a.column3, b.column2 from Table1 a join Table2 b on a.column1 = b.column1 and a.column2 = b.column2 and a.column3 = b.column3 I m not understanding why u r not getting any return, can you put ur code here so we can find out mistake. Thanks Please click on " Accepted Answer " if it helps you

Pravin More · Answer

@Akash, ofcourse you can have join on them see, we apply join on two tables n here you hav 1 common column between table1 n table 2 and table2 n table 3...... so can have join. e.g:- select * from table1 t1 join table2 t2 on t1.t1colmn=t2.t1colmn join table3 t3 on t2.t2colmn=t3.t2colmn thats it...... Thanks, Pravin.

Akash Ahlawat · Answer

@Pravin..pls tell me one more thing..I hav three table out of which 1st and 2nd table hav one same column and 2nd and 3rd have two same column..but all three tables doesnt have any same column..is it possible to hav a join on them and how??

Akash Ahlawat · Answer

@Pravin..pls tell me one more thing..I hav three table out of which 1st and 2nd table hav one same column and 2nd and 3rd have two same column..but all three tables doesnt have any same column..is it possible to hav a join on them and how??

Pravin More · Answer

@Akash...yes columns are same but data in 2 tables might be different n not exactly matching for all 3 conditions......because alec put join on all 3 columns.

Akash Ahlawat · Answer

But all 3 columns are perfectly same..is this error is possible due to redundancy

Pravin More · Answer

Hi Alec, no, its not necessary to have join on single column...... but data is not coming might be because of their is no matching data for strictly all 3 joins......so better is put join on single peimary key column. Thanks, Pravin.

Problem in using joins on table

Answers (8)