# Crate SQL HTTP Endpoint

Crate provides a HTTP Endpoint that can be used to submit SQL queries. The endpoint is accessible under <servername:port>/_sql

SQL statements are sent to the _sql endpoint in json format, whereby the statement is sent as value associated to the key stmt”.

See also

`language`

A simple SELECT statement can be submitted like this:

    sh$ curl -sSXPOST 'localhost:9200/_sql?pretty' -d '{
    ... "stmt":"select name, position from locations order by \"_id\" limit 2"
    ... }'
    {
      "cols" : [ "name", "position" ],
      "rows" : [ [ "North West Ripple", 1 ], [ "Arkintoofle Minor", 3 ] ]
    }

In addition to the stmt key the request body may also contain an args key which can be used for SQL parameter substitution.

The SQL statement has to be changed to use placeholders where the values should be inserted. Placeholders can either bei numbered (in the form of $1, $2, etc.) or unnumbered using a question mark ?

The placeholders will then be substituted with values from an array that is expected under the args key:

    sh$ curl -sSXPOST 'localhost:9200/_sql?pretty' -d@- <<- EOF
    ... {"stmt":
    ...     "select date,position from locations
    ...     where date <= \$1 and position < \$2 order by position",
    ...  "args": ["1979-10-12", 3]
    ... }
    ... EOF
    {
      "cols" : [ "date", "position" ],
      "rows" : [ [ "1979-10-12T00:00:00.000Z", 1 ],
                 [ "1979-10-12T00:00:00.000Z", 2 ] ]
    }

Note

In this example the placeholders start with an backslash due to shell escaping.

The same query using question marks as placeholders looks like this:

    sh$ curl -sSXPOST 'localhost:9200/_sql?pretty' -d@- <<- EOF
    ... {"stmt":
    ...     "select date,position from locations
    ...     where date <= ? and position < ? order by position",
    ...  "args": ["1979-10-12", 3]
    ... }
    ... EOF
    {
      "cols" : [ "date", "position" ],
      "rows" : [ [ "1979-10-12T00:00:00.000Z", 1 ],
                 [ "1979-10-12T00:00:00.000Z", 2 ] ]
    }

## Error Handling

Queries that are invalid or cannot be satisfied will result in an error response. The response will contain an error code, an error message and in some cases additional arguments that are specific to the error code.

Client libraries should use the error code to translate the error into an appropriate exception:

    sh$ curl -sSXPOST 'localhost:9200/_sql?pretty' -d '{
    ... "stmt":"select name, position"
    ... }'
    {
      "error" : {
        "message" : "SQLParseException[Only exactly one from table is allowed, got: 0]",
        "code" : 4000
      }
    }

To get more insight into what exactly went wrong an additional error_trace GET parameter can be specified to return the stack trace:

    sh$ curl -sSXPOST 'localhost:9200/_sql?pretty&error_trace=True' -d '{
    ... "stmt":"select name, position"
    ... }'
    {
      "error" : {
        "message" : "SQLParseException[Only exactly one from table is allowed, got: 0]",
        "code" : 4000
      },
      "error_trace" : {
        "message" : "Only exactly one from table is allowed, got: 0",
        "at" : {
          "class" : "org.cratedb.action.parser.XContentGenerator",
          "method" : "generate",
          "file" : "XContentGenerator.java",
          "line" : ...
        },
        "at" : {
          "class" : "org.cratedb.action.parser.XContentGenerator",
          "method" : "generate",
          "file" : "XContentGenerator.java",
          "line" : ...
        },
    ...

Note

This parameter is intended for crate developers or for users requesting support for Crate. Client libraries shouldn’t make use of this option and not include the stacktrace.

Currently the defined error codes are:

> Code | Error
> --- | ---
> 1000 | Generic undefined error
> 4000 | The statement contains an invalid syntax or unsupported SQL statement
> 4091 | A document with the same primary key exists already.
> 4092 | A VersionConflict. Might be thrown if an attempt was made to update the same document concurrently.