pg-query-parser/README.md

The real PostgreSQL query parser

# pg-query-parser

The real PostgreSQL parser for nodejs. The primary objective of this module is to provide symmetric parsing
and deparsing of SQL statements. With this module you can modify parts of a SQL query statement and
serialize the query tree back into a formatted SQL statement. It uses the *real* [PostgreSQL parser](https://github.com/lfittl/libpg_query).

The main functionality provided by this module is deparsing, which PostgreSQL does not have internally.

## Installation

```sh
npm install pg-query-parser
```

## Example

Rewrite part of a SQL query:

```js
const parser = require('pg-query-parser');

const query = parser.parse('SELECT * FROM test_table').query;

query[0].SelectStmt.fromClause[0].RangeVar.relname = 'another_table';

console.log(parser.deparse(query));

// SELECT * FROM "another_table"
```

### Documentation

### `parser.parse(sql)`

Parses the query and returns a parse object.

### Parameters

| parameter            | type               | description                                               |
| -------------------- | ------------------ | --------------------------------------------------------- |
| `query`              | String             | SQL query                                                 |

Returns an object in the format:

```
{ query: <query|Object>,
  error: { message: <message|String>,
           fileName: <fileName|String>,
           lineNumber: <line|Number>,
           cursorPosition: <cursor|Number> }
```

### `parser.deparse(query)`

Deparses the query tree and returns a formatted SQL statement. This function takes as input a query AST
in the same format as the `query` property of on the result of the `parse` method. This is the primary
functionality of this module.

### Parameters

| parameter            | type               | description                                               |
| -------------------- | ------------------ | --------------------------------------------------------- |
| `query`              | Object             | Query tree obtained from `parse`                          |

Returns a normalized formatted SQL string.

## Related

* [pg-query-native](https://github.com/zhm/node-pg-query-native)
* [libpg_query](https://github.com/lfittl/libpg_query)
* [pg_query](https://github.com/lfittl/pg_query)
* [pg_query.go](https://github.com/lfittl/pg_query.go)