Builds a Join Query, by adding another dataobject to this one. Be careful when using this, raw queries may be clearer than using joinAdd.
Thanks to Stijn de Reede for the implementation of this.
object $obj - joining object (no value resets the join)
string $joinType - "LEFT" | "INNER " | "RIGHT" | ""
INNER is default, "" indicates just select ... from a,b,c with no join and links are added as where items.
string $joinAs - if you want to select the table as anther name useful when you want to select multiple columns from a secondary table.
string $joinCol - The column on This objects table to match,needed if this table links to the child object in multiple places eg.
Example 26-1. using specific join Columns
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This function can not be called statically.
The Examples below are not tested, use DB_DataObject::debugLevel(1), to see what exactly is going on when you use this, and send the author some better examples..
Example 26-2. Simple simple Join
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Example 26-3. Resulting SQL
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Example 26-4. More Complex Join query
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Example 26-5. Resulting SQL
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