Send the prepared statement

For a prepared statement to be executed, you must send it to the database server with one of the following DataBlade® API functions.
DataBlade API function When to use
mi_exec_prepared_statement() If the prepared statement does not return rows

If the prepared statement does return rows but you only need to access these rows sequentially (with an implicit cursor)
mi_open_prepared_statement() If the prepared statement does return rows and you need to perform one of the following tasks:
  • Access these rows with a scroll, update, or hold cursor (instead of a read-only sequential cursor)
  • Control how many rows the database server puts into the cursor at one time
Both these functions support the following parameters.
Parameter Description
stmt_desc Is a pointer to a statement descriptor for the prepared statement

The mi_prepare() function generates this statement descriptor.
control flag Determines whether any query rows are in binary or text representation
params_are_binary Indicates whether the input-parameter values are in binary or text representation
n_params Is the number of input-parameter values in the input-parameter-value arrays
Input-parameter-value arrays:
  • values
  • types
  • lengths
  • nulls
 Arrays that contain the following information for each input-parameter value:
  • Value
  • Data type
  • Length (for varying-length data types)
  • Whether the input-parameter value is an SQL NULL value
retlen The number of column values that are in each retrieved row
rettypes An array that contains the data types of any returned column values
After the database server executes the prepared statement, the statement becomes the current statement. The database server sends back the statement results, including whether the current statement was successful. Obtain the status of the current statement with the mi_get_result() function.
Tip: The return value that the mi_exec_prepared_statement() or mi_open_prepared_statement() function returns does not indicate the success of the current statement. It indicates if mi_exec_prepared_statement() or mi_open_prepared_statement() was able to successfully send the prepared statement to the database server.