world.DatabaseColumns
Find how many columns will be returned by an SQL statement
Prototype
long DatabaseColumns(BSTR DbName);Description
You can use this, after successfully doing a DatabasePrepare, to find the number of columns that each row will return. This number might be zero for SQL statements that do not return any data.
You can do this before doing a DatabaseStep, because the column names (and number of columns) is a property of the SQL statement, whether or not any rows are found that actually match the query.
Lua example
columns = DatabaseColumns ("db")Return value
A positive integer, or zero, representing the number of columns that the prepared SQL statement will return.
Otherwise, an error code:
-1 : Database id not found
-2 : Database not open
-4 : Do not have prepared statement
Related topic
See also
| Function | Description |
|---|---|
| DatabaseColumnName | Find the name of a specified column returned by an SQL statement |
| DatabaseColumnNames | Return a table of all the columns returned by an SQL statement |
| DatabaseColumnText | Returns the contents of an SQL column, as text |
| DatabaseColumnType | Returns the type of data in an SQL column |
| DatabaseColumnValue | Returns the contents of an SQL column, as text, float, integer, or null |
| DatabaseColumnValues | Returns the contents of all the SQL columns after a step |
| DatabaseError | Returns an English string describing the most recent SQL error |
| DatabaseExec | Executes SQL code against an SQLite database |
| DatabaseFinalize | Finalizes (wraps up) a previously-prepared SQL statement |
| DatabaseLastInsertRowid | Returns the most recently automatically allocated database key |
| DatabaseOpen | Opens an SQLite database |
| DatabasePrepare | Prepares an SQL statement for execution |
| DatabaseReset | Resets a previously-prepared SQL statement to the start |