msys.db.execute

msys.db.execute — Execute a query that is not expected to return data

success, errmsg = msys.db.execute(cachename, query, queryparams, options);

Execute a query that is not expected to return data. The parameters are as follows:

• cachename – Name of the datasource cache to be queried

• query – Query to be presented to the cache

  The query may use placeholder characters in the form :name, ?, or $name depending on the underlying driver. If the ? placeholder is used, then queryparams must be a table with numeric keys, with index 1 corresponding to the first ? in the query string. Otherwise, the keys must be string keys with names that match up to the defined parameters. For instance, $name or :name expect to find a parameter in the table using the key name; the leading $ or : is removed before looking up the value.

• queryparams – Lua table object with parameters to bind into the query

  Note#

  The SQL standard requires the use of the "IS [NOT] NULL" syntax in a predicate for matching against NULL. A predicate "field_name = ?" would result in an error if a query parameter is NULL. A Lua nil is equivalent to an SQL NULL.

• options – Lua table object containing additional options that affect this query

  If options is specified, it must be a table. The following options are permitted:

  • nocache – Boolean value. If set to true, bypass the cache and force the query to be presented to the underlying datasource.

  • raise_error – Boolean value. If set to true, raise an exception (lua_error) on error containing the error string. Default value is true.

Enable this function with the statement require('msys.db'); and also include the statement require('msys.datasource');.

This function returns the following:

• If query succeeds – Returns true.

• If query fails and raise_error is set to false – Returns false indicating query faliure and errmsg indicating what failed.

• If the query fails and raise_error is set to true – Raises an exception.

The idiom for issuing a query and working with the results is:

The data cache used in the preceding example must be defined in your configuration file. For more information, see “ds_core - Datasource Query Core”.

msys.db.query, msys.db.fetch_row, “Policy Scriptlets”