&<

📄字数 274

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功能描述

如果 A 的边界框与 B 的边界框重叠，或在 B 的边界框的左侧，或者更准确地说，A 的边界框不位于 B 的边界框的右侧，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。

示例

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

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

(3 rows)