List out the drupal query functions

The following query functions are used in

db_connect - Initialize a database connection.

db_query - Execute query

db_result - Return an individual result field from the previous query.

db_affected_rows - Determine the number of rows changed by the preceding query.

db_rewrite_sql - Rewrites node, taxonomy and comment queries. Use it for listing queries

db_create_table -Create a new table from a Drupal table definition.

db_field_names - Return an array of field names from an array of key/index column specifiers.

db_query_range - Runs a limited-range query in the active database.

db_fetch_array - Fetch one result row from the previous query as an array

db_fetch_object - Fetch one result row from the previous query as an object.

db_error - Determine whether the previous query caused an error.

db_lock_table - Lock a table.

db_unlock_tables - Unlock all locked tables.

db_table_exists - Check if a table exists.

db_column_exists - Check if a column exists in the given table.