Difference between revisions of "SQLCHECKUNIQUE()"
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Yvonne.milne (Talk | contribs) (Created page with "''Under Construction'' ==Purpose== Function to check whether a column value is unique ==Syntax== SQLCHECKUNIQUE(<cTable>, <cKeyField>, <cKeyValue>) ==See Also== KEYLOOKUP...") |
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==Purpose== | ==Purpose== | ||
| − | Function to check whether a column value is unique | + | Function to check whether a prospective column value is unique |
==Syntax== | ==Syntax== | ||
| − | SQLCHECKUNIQUE(<cTable>, <cKeyField>, <cKeyValue>) | + | SQLCHECKUNIQUE(<cTable>, <cKeyField>, <cKeyValue>[, <lAllowblank>[, <lAllownull>]]) |
==See Also== | ==See Also== | ||
| Line 11: | Line 9: | ||
==Description== | ==Description== | ||
| − | The SQLCHECKUNIQUE() function checks the uniqueness of a column value. The function will auto-detect if the specified table is a native Lianja table or a Virtual Table and act accordingly. | + | The SQLCHECKUNIQUE() function checks the uniqueness of a prospective column value. The function will auto-detect if the specified table is a native Lianja table or a Virtual Table and act accordingly. |
You should always provide a fully qualified database!table if your app is to work in Web/Mobile e.g "southwind!employees". | You should always provide a fully qualified database!table if your app is to work in Web/Mobile e.g "southwind!employees". | ||
| + | |||
| + | The numeric return value is 1 if the cKeyValue value already exists and 0 if it does not already exist in the cKeyField table column. | ||
{| class="wikitable" width="100%" | {| class="wikitable" width="100%" | ||
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|valign="top"|cKeyValue||Character expression containing the value to be compared against cKeyField. If this is a character field then enclose it in quotes within quotes: " 'string' ". If it is a numeric then enclose it like this "1". | |valign="top"|cKeyValue||Character expression containing the value to be compared against cKeyField. If this is a character field then enclose it in quotes within quotes: " 'string' ". If it is a numeric then enclose it like this "1". | ||
| + | |- | ||
| + | |valign="top"|lAllowblank||Logical expression specifying whether blank values should be ignored. | ||
| + | |- | ||
| + | |valign="top"|lAllownull||Logical expression specifying whether null values should be ignored. | ||
|- | |- | ||
|} | |} | ||
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==Example== | ==Example== | ||
<code lang="recital"> | <code lang="recital"> | ||
| − | + | // Character cKeyfield | |
| + | nCustIDUnique = sqlcheckunique("southwind!customers","customerid","'ALFKI'") | ||
| + | // Numeric cKeyfield | ||
| + | nEmpIDUnique = sqlcheckunique("southwind!employees","employeeid","3") | ||
</code> | </code> | ||
Revision as of 04:48, 24 April 2020
Contents
Purpose
Function to check whether a prospective column value is unique
Syntax
SQLCHECKUNIQUE(<cTable>, <cKeyField>, <cKeyValue>[, <lAllowblank>[, <lAllownull>]])
See Also
KEYLOOKUP(), LOOKUP(), RLOOKUP(), SEEK(), SET RELATION, SQLLOOKUP()
Description
The SQLCHECKUNIQUE() function checks the uniqueness of a prospective column value. The function will auto-detect if the specified table is a native Lianja table or a Virtual Table and act accordingly.
You should always provide a fully qualified database!table if your app is to work in Web/Mobile e.g "southwind!employees".
The numeric return value is 1 if the cKeyValue value already exists and 0 if it does not already exist in the cKeyField table column.
| Keywords | Description |
|---|---|
| cTable | Character expression to specify the table to be checked (native or Virtual Table). |
| cKeyField | Character expression to specify the column in the table to be checked. |
| cKeyValue | Character expression containing the value to be compared against cKeyField. If this is a character field then enclose it in quotes within quotes: " 'string' ". If it is a numeric then enclose it like this "1". |
| lAllowblank | Logical expression specifying whether blank values should be ignored. |
| lAllownull | Logical expression specifying whether null values should be ignored. |
Example
// Character cKeyfield nCustIDUnique = sqlcheckunique("southwind!customers","customerid","'ALFKI'") // Numeric cKeyfield nEmpIDUnique = sqlcheckunique("southwind!employees","employeeid","3")
