Debugging

Execsql includes several metacommands that will display elements of its internal environment, to assist with script debugging.

DEBUG LOG [LOCAL] [USER] SUBVARS

Writes substitution variables to the log file. If the LOCAL keyword is used, only the local variables are logged. If the USER keyword is used, no system, data, or environment variables are logged.

DEBUG WRITE [LOCAL] [USER] SUBVARS [[APPEND] TO <filename>]

Writes all substitution variables to the terminal or to the specified text file. Local variables in the current context are always included. If the LOCAL keyword is used, only the local variables are written. If the USER keyword is used, no system, data, or environment variables are written.

DEBUG LOG CONFIG

Writes configuration settings to the log file.

DEBUG WRITE CONFIG [[APPEND] TO <filename>]

Writes configuration settings to the console or to the specified text file.

DEBUG WRITE ODBC_DRIVERS [[APPEND] TO <filename>]

Writes the names of available ODBC drivers to the console or to the specified text file. ODBC drivers are used with SQL Server and MS-Access.

DEBUG WRITE <script_name> [[APPEND] TO <filename>]

This is an alias for the WRITE SCRIPT metacommand.

The ON ERROR_HALT metacommands allow custom reporting (or cleanup) actions to be taken when errors occur.

Setting the configuration setting write_warnings to “Yes” can also assist with debugging by displaying conditions that may result from errors in the script.

Error Messages and Reporting

When execsql encounters an error it will print an error message that includes the command that caused the error, the line number in the script being processed, and the line number in execsql.py. These messages will appear similar to the following:

**** Error in metacommand.
Line 19 of script bad_import_statement.sql
Unknown metacommand
import to replacment staging.locs from locations.csv with quote " delimiter ,
Metacommand: import to replacment staging.locs from locations.csv with quote " delimiter ,
Error occurred at 2016-09-28 21:30:50 UTC.

Error messages may result from:

  • Typographic or syntax errors in metacommands (as above) or SQL statements.
  • SQL statements that are inconsistent with the database structure or that violate data type, integrity, or check constraints–that is, errors that originate from the DBMS.
  • Character encoding inconsistencies, particularly with data being imported.
  • Bugs in execsql.

If an error is evidently caused by a bug in execsql, the problem can be logged in the issue tracker.