Two standard spatial data formats are used to represent geometry objects in queries:两种标准空间数据格式用于表示查询中的几何图形对象：
Well-Known Text (WKT) format众所周知的文本（WKT）格式
Well-Known Binary (WKB) format众所周知的二进制（WKB）格式
Internally, MySQL stores geometry values in a format that is not identical to either WKT or WKB format. (Internal format is like WKB but with an initial 4 bytes to indicate the SRID.)在内部，MySQL以与WKT或WKB格式不同的格式存储几何体值。（内部格式类似于WKB，但最初有4个字节来指示SRID。）
There are functions available to convert between different data formats; see Section 12.17.6, “Geometry Format Conversion Functions”.有一些功能可用于在不同的数据格式之间进行转换；参见第12.17.6节，“几何格式转换函数”。
The following sections describe the spatial data formats MySQL uses:以下部分介绍MySQL使用的空间数据格式：
The Well-Known Text (WKT) representation of geometry values is designed for exchanging geometry data in ASCII form. The OpenGIS specification provides a Backus-Naur grammar that specifies the formal production rules for writing WKT values (see Section 11.4, “Spatial Data Types”).几何值的众所周知的文本（WKT）表示是为交换ASCII形式的几何数据而设计的。OpenGIS规范提供了一种Backus-Naur语法，该语法指定了写入WKT值的正式生成规则（参见第11.4节，“空间数据类型”）。
Examples of WKT representations of geometry objects:几何图形对象的WKT表示示例：
A Point:
POINT(15 20)
The point coordinates are specified with no separating comma. 点坐标的指定不使用分隔逗号。This differs from the syntax for the SQL 这与SQL Point() function, which requires a comma between the coordinates. Point()函数的语法不同，后者需要在坐标之间使用逗号。Take care to use the syntax appropriate to the context of a given spatial operation. 注意使用适合给定空间操作上下文的语法。For example, the following statements both use 例如，以下语句都使用ST_X() to extract the X-coordinate from a Point object. The first produces the object directly using the Point() function. ST_X()从Point对象提取X坐标。第一个直接使用Point()函数生成对象。The second uses a WKT representation converted to a 第二个使用转换为Point with ST_GeomFromText().Point的WKT表示，该表示使用ST_GeomFromText()。
mysql>SELECT ST_X(Point(15, 20));+---------------------+ | ST_X(POINT(15, 20)) | +---------------------+ | 15 | +---------------------+ mysql>SELECT ST_X(ST_GeomFromText('POINT(15 20)'));+---------------------------------------+ | ST_X(ST_GeomFromText('POINT(15 20)')) | +---------------------------------------+ | 15 | +---------------------------------------+
A LineString with four points:LineString具有四个点：
LINESTRING(0 0, 10 10, 20 25, 50 60)
The point coordinate pairs are separated by commas.点坐标对用逗号分隔。
A Polygon with one exterior ring and one interior ring:Polygon具有一个外环和一个内环：
POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))
A MultiPoint with three Point values:MultiPoint具有三个Point值：
MULTIPOINT(0 0, 20 20, 60 60)
Spatial functions such as 空间函数，如ST_MPointFromText() and ST_GeomFromText() that accept WKT-format representations of MultiPoint values permit individual points within values to be surrounded by parentheses. For example, both of the following function calls are valid:ST_MPointFromText()和ST_GeomFromText()接受MultiPoint值的WKT格式表达允许值中的各个点用括号括起来。例如，以下两个函数调用都是有效的：
ST_MPointFromText('MULTIPOINT (1 1, 2 2, 3 3)')
ST_MPointFromText('MULTIPOINT ((1 1), (2 2), (3 3))')A 具有两个MultiLineString with two LineString values:LineString值的MultiLineString：
MULTILINESTRING((10 10, 20 20), (15 15, 30 15))
A 具有两个MultiPolygon with two Polygon values:Polygon值的MultiPolygon：
MULTIPOLYGON(((0 0,10 0,10 10,0 10,0 0)),((5 5,7 5,7 7,5 7, 5 5)))
A 由两个GeometryCollection consisting of two Point values and one LineString:Point值和一个LineString组成的GeometryCollection：
GEOMETRYCOLLECTION(POINT(10 10), POINT(30 30), LINESTRING(15 15, 20 20))
The Well-Known Binary (WKB) representation of geometric values is used for exchanging geometry data as binary streams represented by 几何值的公知二进制（WKB）表示用于将几何数据交换为由包含几何WKB信息的BLOB values containing geometric WKB information. BLOB值表示的二进制流。This format is defined by the OpenGIS specification (see Section 11.4, “Spatial Data Types”). It is also defined in the ISO SQL/MM Part 3: Spatial standard.该格式由OpenGIS规范定义（参阅第11.4节，“空间数据类型”）。它也在ISO SQL/MM第3部分：空间标准中进行了定义。
WKB uses 1-byte unsigned integers, 4-byte unsigned integers, and 8-byte double-precision numbers (IEEE 754 format). A byte is eight bits.WKB使用1字节无符号整数、4字节无符号整型和8字节双精度数字（IEEE 754格式）。一个字节是八位。
For example, a WKB value that corresponds to 例如，对应于POINT(1 -1) consists of this sequence of 21 bytes, each represented by two hexadecimal digits:POINT(1-1)的WKB值由21个字节的序列组成，每个字节由两个十六进制数字表示：
0101000000000000000000F03F000000000000F0BF
The sequence consists of the components shown in the following table.该序列由下表所示的组件组成。
Table 11.2 WKB Components Example表11.2 WKB组件示例
| Component | Size | Value |
|---|---|---|
| Byte order | 1 byte | 01 |
| WKB type | 4 bytes | 01000000 |
| X coordinate | 8 bytes | 000000000000F03F |
| Y coordinate | 8 bytes | 000000000000F0BF |
Component representation is as follows:组件表示如下：
The byte order indicator is either 1 or 0 to signify little-endian or big-endian storage. 字节顺序指示符是1或0，表示小端或大端存储。The little-endian and big-endian byte orders are also known as Network Data Representation (NDR) and External Data Representation (XDR), respectively.小端字节顺序和大端字节顺序也分别称为网络数据表示（NDR）和外部数据表示（XDR）。
The WKB type is a code that indicates the geometry type. WKB类型是指示几何图形类型的代码。MySQL uses values from 1 through 7 to indicate MySQL使用从1到7的值来表示Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection.Point、LineString、Polygon、MultiPoint、MultiLineString、MultiPolygon和GeometryCollection。
A Point value has X and Y coordinates, each represented as a double-precision value.Point值具有X和Y坐标，每一个坐标都表示为双精度值。
WKB values for more complex geometry values have more complex data structures, as detailed in the OpenGIS specification.更复杂的几何图形值的WKB值具有更复杂的数据结构，如OpenGIS规范中所述。
MySQL stores geometry values using 4 bytes to indicate the SRID followed by the WKB representation of the value. For a description of WKB format, see Well-Known Binary (WKB) Format.MySQL使用4个字节存储几何体值，以指示SRID和值的WKB表示形式。有关WKB格式的描述，请参阅众所周知的二进制（WKB）格式。
For the WKB part, these MySQL-specific considerations apply:对于WKB部分，以下MySQL特定注意事项适用：
The byte-order indicator byte is 1 because MySQL stores geometries as little-endian values.字节顺序指示符字节是1，因为MySQL将几何图形存储为小端值。
MySQL supports geometry types of MySQL支持Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection. Other geometry types are not supported.Point、LineString、Polygon、MultiPoint、MultiLineString、MultiPolygon和GeometryCollection等几何图形类型。不支持其他几何图形类型。
Only 只有GeometryCollection can be empty. Such a value is stored with 0 elements.GeometryCollection可以为空。这样的值与0个元素一起存储。
Polygon rings can be specified both clockwise and counterclockwise. MySQL flips the rings automatically when reading data.多边形环既可以按顺时针方向指定，也可以按逆时针方向指定。MySQL在读取数据时会自动翻转环。
Cartesian coordinates are stored in the length unit of the spatial reference system, with X values in the X coordinates and Y values in the Y coordinates. Axis directions are those specified by the spatial reference system.笛卡尔坐标存储在空间参考系的长度单位中，X值在X坐标中，Y值在Y坐标中。轴方向是由空间参照系统指定的方向。
Geographic coordinates are stored in the angle unit of the spatial reference system, with longitudes in the X coordinates and latitudes in the Y coordinates. Axis directions and the meridian are those specified by the spatial reference system.地理坐标存储在空间参考系的角度单位中，经度在X坐标中，纬度在Y坐标中。轴方向和子午线是由空间参考系统指定的方向。
The LENGTH() function returns the space in bytes required for value storage. Example:LENGTH()函数返回值存储所需的空间（以字节为单位）。例如：
mysql>SET @g = ST_GeomFromText('POINT(1 -1)');mysql>SELECT LENGTH(@g);+------------+ | LENGTH(@g) | +------------+ | 25 | +------------+ mysql>SELECT HEX(@g);+----------------------------------------------------+ | HEX(@g) | +----------------------------------------------------+ | 000000000101000000000000000000F03F000000000000F0BF | +----------------------------------------------------+
The value length is 25 bytes, made up of these components (as can be seen from the hexadecimal value):值长度为25字节，由以下组成（从十六进制值中可以看出）：
4 bytes for integer SRID (0)4字节用于整数SRID(0)
1 byte for integer byte order (1 = little-endian)1字节表示整数字节顺序（1=little-endian）
4 bytes for integer type information (1 = 4字节用于整数类型信息（1=Point)Point）
8 bytes for double-precision X coordinate (1)8字节用于双精度X坐标（1）
8 bytes for double-precision Y coordinate (−1)8字节用于双精度Y坐标（-1）