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join multiple table


yanti

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Hi

 

Tables are joined where the info in them is related in some way. Ie, a table of people with a table of hair colours, with the table of people having a column with an id field giving their hair colour which is a key to the table of hair colours.

 

It is these relationships that are important and you need to know these before you can join them together.

 

You can do what is known as a cross join which will get every possible combination. Useful if you have (say) a table of people and a table of days and want a list of people and days which you can then link to other data (such as what they had for breakfast, if they had any). However the number of records will be massive (ie, 2 tables each of 100 rows cross joined together will result in 10000 rows returned). If you 19 tables each had only 10 rows then cross joining them all together would result in 10,000,000,000,000,000,000 being returned!

 

We need more info on your tables and what you want returned before we can give you any useful advice on what to do.

 

All the best

 

Keith

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