# PostgreSQL Functions

## Notes

> Note:

> Not all functions are supported by all builds. It depends on your libpq (The PostgreSQL C client library) version and how libpq is compiled. If PHP PostgreSQL extensions are missing, then it is because your libpq version does not support them.

> Note:

> Most PostgreSQL functions accept `connection` as the optional first parameter. If it is not provided, the last opened connection is used. If it doesn't exist, functions return `false`.

> Note:

> PostgreSQL automatically folds all identifiers (e.g. table/column names) to lower-case values at object creation time and at query time. To force the use of mixed or upper case identifiers, you must escape the identifier using double quotes ("").

> Note:

> PostgreSQL does not have special commands for fetching database schema information (eg. all the tables in the current database). Instead, there is a standard schema named `information_schema` containing system views with all the necessary information, in an easily queryable form. See the » PostgreSQL Documentation for full details.

## Table of Contents

- pg_affected_rows — Returns number of affected records (tuples)
- pg_cancel_query — Cancel an asynchronous query
- pg_client_encoding — Gets the client encoding
- pg_close — Closes a PostgreSQL connection
- pg_connect — Open a PostgreSQL connection
- pg_connect_poll — Poll the status of an in-progress asynchronous PostgreSQL connection attempt
- pg_connection_busy — Get connection is busy or not
- pg_connection_reset — Reset connection (reconnect)
- pg_connection_status — Get connection status
- pg_consume_input — Reads input on the connection
- pg_convert — Convert associative array values into forms suitable for SQL statements
- pg_copy_from — Insert records into a table from an array
- pg_copy_to — Copy a table to an array
- pg_dbname — Get the database name
- pg_delete — Deletes records
- pg_end_copy — Sync with PostgreSQL backend
- pg_escape_bytea — Escape a string for insertion into a bytea field
- pg_escape_identifier — Escape an identifier for insertion into a text field
- pg_escape_literal — Escape a literal for insertion into a text field
- pg_escape_string — Escape a string for query
- pg_execute — Sends a request to execute a prepared statement with given parameters, and waits for the result
- pg_fetch_all — Fetches all rows from a result as an array
- pg_fetch_all_columns — Fetches all rows in a particular result column as an array
- pg_fetch_array — Fetch a row as an array
- pg_fetch_assoc — Fetch a row as an associative array
- pg_fetch_object — Fetch a row as an object
- pg_fetch_result — Returns values from a result instance
- pg_fetch_row — Get a row as an enumerated array
- pg_field_is_null — Test if a field is SQL NULL
- pg_field_name — Returns the name of a field
- pg_field_num — Returns the field number of the named field
- pg_field_prtlen — Returns the printed length
- pg_field_size — Returns the internal storage size of the named field
- pg_field_table — Returns the name or oid of the tables field
- pg_field_type — Returns the type name for the corresponding field number
- pg_field_type_oid — Returns the type ID (OID) for the corresponding field number
- pg_flush — Flush outbound query data on the connection
- pg_free_result — Free result memory
- pg_get_notify — Gets SQL NOTIFY message
- pg_get_pid — Gets the backend's process ID
- pg_get_result — Get asynchronous query result
- pg_host — Returns the host name associated with the connection
- pg_insert — Insert array into table
- pg_last_error — Get the last error message string of a connection
- pg_last_notice — Returns the last notice message from PostgreSQL server
- pg_last_oid — Returns the last row's OID
- pg_lo_close — Close a large object
- pg_lo_create — Create a large object
- pg_lo_export — Export a large object to file
- pg_lo_import — Import a large object from file
- pg_lo_open — Open a large object
- pg_lo_read — Read a large object
- pg_lo_read_all — Reads an entire large object and send straight to browser
- pg_lo_seek — Seeks position within a large object
- pg_lo_tell — Returns current seek position a of large object
- pg_lo_truncate — Truncates a large object
- pg_lo_unlink — Delete a large object
- pg_lo_write — Write to a large object
- pg_meta_data — Get meta data for table
- pg_num_fields — Returns the number of fields in a result
- pg_num_rows — Returns the number of rows in a result
- pg_options — Get the options associated with the connection
- pg_parameter_status — Looks up a current parameter setting of the server
- pg_pconnect — Open a persistent PostgreSQL connection
- pg_ping — Ping database connection
- pg_port — Return the port number associated with the connection
- pg_prepare — Submits a request to the server to create a prepared statement with the given parameters, and waits for completion
- pg_put_line — Send a NULL-terminated string to PostgreSQL backend
- pg_query — Execute a query
- pg_query_params — Submits a command to the server and waits for the result, with the ability to pass parameters separately from the SQL command text
- pg_result_error — Get error message associated with result
- pg_result_error_field — Returns an individual field of an error report
- pg_result_memory_size — Returns the amount of memory allocated for a query result
- pg_result_seek — Set internal row offset in result instance
- pg_result_status — Get status of query result
- pg_select — Select records
- pg_send_execute — Sends a request to execute a prepared statement with given parameters, without waiting for the result(s)
- pg_send_prepare — Sends a request to create a prepared statement with the given parameters, without waiting for completion
- pg_send_query — Sends asynchronous query
- pg_send_query_params — Submits a command and separate parameters to the server without waiting for the result(s)
- pg_set_chunked_rows_size — Set the query results to be retrieved in chunk mode
- pg_set_client_encoding — Set the client encoding
- pg_set_error_context_visibility — Determines the visibility of the context's error messages returned by pg_last_error and pg_result_error
- pg_set_error_verbosity — Determines the verbosity of messages returned by pg_last_error and pg_result_error
- pg_socket — Get a read only handle to the socket underlying a PostgreSQL connection
- pg_trace — Enable tracing a PostgreSQL connection
- pg_transaction_status — Returns the current in-transaction status of the server
- pg_tty — Return the TTY name associated with the connection
- pg_unescape_bytea — Unescape binary for bytea type
- pg_untrace — Disable tracing of a PostgreSQL connection
- pg_update — Update table
- pg_version — Returns an array with client, protocol and server version (when available)

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