Categories:

Geospatial functions, Conversion functions

TO_GEOGRAPHY

Parses an input and returns a value of type GEOGRAPHY.

See also:

TRY_TO_GEOGRAPHY , ST_GEOGRAPHYFROMWKB , ST_GEOGRAPHYFROMWKT

Syntax

Use one of the following:

TO_GEOGRAPHY( <varchar_expression> [ , <allow_invalid> ] )

TO_GEOGRAPHY( <binary_expression> [ , <allow_invalid> ] )

TO_GEOGRAPHY( <variant_expression> [ , <allow_invalid> ] )

TO_GEOGRAPHY( <geometry_expression> [ , <allow_invalid> ] )

Arguments

Required:

varchar_expression

The argument must be a string expression that represents a valid geometric object in one of the following formats:

  • WKT (well-known text).
  • WKB (well-known binary) in hexadecimal format (without a leading 0x).
  • EWKT (extended well-known text).
  • EWKB (extended well-known binary) in hexadecimal format (without a leading 0x).
  • GeoJSON.
binary_expression

The argument must be a binary expression in WKB or EWKB format.

variant_expression

The argument must be an OBJECT in GeoJSON format.

geometry_expression

The argument must be an expression of type GEOMETRY with the SRID 4326.

Optional:

allow_invalid

If TRUE, specifies that the function returns a GEOGRAPHY or GEOMETRY object, even when the input shape isn’t valid and can’t be repaired. For more information, see Specifying how invalid geospatial shapes are handled.

Returns

The function returns a value of type GEOGRAPHY.

Usage notes

  • Issues an error if the input cannot be parsed as one of the supported formats (WKT, WKB, EWKT, EWKB, GeoJSON).
  • Issues an error if the input format is EWKT or EWKB and the SRID is not 4326. See the note on EWKT and EWKB handling.
  • To construct a GEOGRAPHY object from WKT or EWKT input, you can also use ST_GEOGRAPHYFROMWKT.
  • To construct a GEOGRAPHY object from WKB or EWKB input, you can also use ST_GEOGRAPHYFROMWKB.
  • For the coordinates in WKT, EWKT, and GeoJSON, longitude appears before latitude (for example, POINT(lon lat)).

Examples

This shows a simple use of the TO_GEOGRAPHY function with VARCHAR data:

select TO_GEOGRAPHY('POINT(-122.35 37.55)');
+--------------------------------------+
| TO_GEOGRAPHY('POINT(-122.35 37.55)') |
|--------------------------------------|
| POINT(-122.35 37.55)                 |
+--------------------------------------+

The following example returns the GEOGRAPHY object for a geospatial object with a Z coordinate described in WKT format:

select TO_GEOGRAPHY('POINTZ(-122.35 37.55 30)');
+------------------------------------------+
| TO_GEOGRAPHY('POINTZ(-122.35 37.55 30)') |
|------------------------------------------|
| POINTZ(-122.35 37.55 30)                 |
+------------------------------------------+