Difference between revisions of "REFERENCES()"
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==Purpose== | ==Purpose== | ||
Function to perform a cross-table lookup for a specified key expression | Function to perform a cross-table lookup for a specified key expression | ||
− | |||
==Syntax== | ==Syntax== | ||
REFERENCES(<key expression>, <workarea | alias> [,<tag name>]) | REFERENCES(<key expression>, <workarea | alias> [,<tag name>]) | ||
+ | REFERENCES(<key expression>, <table name>, <tag name>) | ||
==See Also== | ==See Also== | ||
− | [[ALIAS() | + | [[ALIAS()]], [[INDEX]], [[KEY()]], [[KEYMATCH()]], [[LOOKUP()]], [[RLOOKUP()]], [[SEEK]], [[SEEK()]], [[SET RELATION]], [[TAG()]], [[TAGCOUNT()]], [[TAGNO()]] |
− | + | ||
==Description== | ==Description== | ||
The REFERENCES() function looks up the specified <key expression> in the master tag index of the specified <workarea | alias>. The <workarea | alias> is the workarea or alias name of an open table. To search in a tag index which is not the current master index, the optional <tag name> parameter can be used. The tag name must be specified as a string. | The REFERENCES() function looks up the specified <key expression> in the master tag index of the specified <workarea | alias>. The <workarea | alias> is the workarea or alias name of an open table. To search in a tag index which is not the current master index, the optional <tag name> parameter can be used. The tag name must be specified as a string. | ||
+ | |||
+ | If the target table is not open, but is in the active database, it can be specified as a string: <table name>. The tag name <tag name> string must also be specified. | ||
The REFERENCES() function returns True (.T.) or False (.F.), depending on the success of the lookup operation. | The REFERENCES() function returns True (.T.) or False (.F.), depending on the success of the lookup operation. | ||
Please see the RLOOKUP() function for cross-table lookups using single indexes (.ndx). | Please see the RLOOKUP() function for cross-table lookups using single indexes (.ndx). | ||
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==Example== | ==Example== | ||
<code lang="recital"> | <code lang="recital"> | ||
− | use | + | open database southwind |
− | + | use customers order customerid in 2 | |
− | + | use orders in 1 | |
− | + | ? references(customerid,2) | |
− | ? references( | + | .T. |
+ | ? references(customerid,customers) | ||
.T. | .T. | ||
− | |||
+ | select customers | ||
+ | set order to address | ||
+ | select orders | ||
+ | // Specify the index tag string to search in non-master index | ||
+ | ? references(customerid,2,"customerid") | ||
+ | .T. | ||
+ | ? references(customerid,customers,"customerid") | ||
+ | .T. | ||
+ | |||
+ | select customers | ||
+ | use | ||
+ | select orders | ||
+ | // customers table is not currently open | ||
+ | ? references(customerid,"customers","customerid") | ||
+ | .T. | ||
+ | </code> | ||
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[[Category:Documentation]] | [[Category:Documentation]] | ||
[[Category:Functions]] | [[Category:Functions]] | ||
− | [[Category: | + | [[Category:Cursor Functions]] |
− | + | ||
− | + | ||
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Latest revision as of 09:00, 28 October 2019
Contents
Purpose
Function to perform a cross-table lookup for a specified key expression
Syntax
REFERENCES(<key expression>, <workarea | alias> [,<tag name>])
REFERENCES(<key expression>,