<<

📄字数 266

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功能描述

如果 A 的边界框严格位于 B 的边界框的左侧，则<<操作符返回TRUE。

语法格式

BOOLEAN <<( GEOMETRY A , GEOMETRY B );

参数说明

• A：目标 GEOMETRY 对象。
• B：目标 GEOMETRY 对象。

函数返回类型

BOOLEAN 类型

使用说明

1. 该操作符将利用几何上可能可用的任何索引。
2. 该操作符支持圆形字符串和曲线。
3. 该操作符支持多面体曲面。

示例

SQL> SELECT tbl1.c1 AS t1_c1, tbl2.c1 AS t2_c1, tbl1.goem << tbl2.goem AS left
           FROM (
           SELECT 1 AS c1, 'LINESTRING(1 2, 1 5)'::GEOMETRY AS goem ) AS tbl1,
           (
           SELECT 2 AS c1, 'LINESTRING(0 0, 4 3)'::GEOMETRY AS goem UNION ALL
           SELECT 3 AS c1, 'LINESTRING(6 0, 6 5)'::GEOMETRY AS goem UNION ALL
           SELECT 4 AS c1, 'LINESTRING(2 2, 5 6)'::GEOMETRY AS goem
           ) AS tbl2;

+-------+-------+------+
| T1_C1 | T2_C1 | LEFT |
+-------+-------+------+
| 1     | 2     | F    |
| 1     | 3     | T    |
| 1     | 4     | T    |
+-------+-------+------+

(3 rows)