最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
The PostgreSQL SELECT statement is used to select data from the database.
The results are stored in a result table called the result set. The syntax format of the SELECT statement is as follows: Column1, column2,…columnN is the field name in the table. Table_name is the table name. If we want to read all the data in the table, we can use the following SQL statement: In the previous chapter INSERT INTO 语句 We have inserted some data into the table company, and use the* sign to read all the data in the table: We can also read the specified fields ID and NAME: 5.14.1. Grammar ¶
SELECT column1, column2,...columnN FROM table_name;
SELECT * FROM table_name;
runoobdb=# SELECT * FROM company; ID NAME AGE ADDRESS SALARY JOIN_DATE ---- ---------- ----- ---------- ------- -------- 1 Paul 32 California 20000.0 2001-07-13 2 Allen 25 Texas 2007-12-13 3 Teddy 23 Norway 20000.0 4 Mark 25 Rich-Mond 65000.0 2007-12-13 5 David 27 Texas 85000.0 2007-12-13
runoobdb=# SELECT ID,NAME FROM company; id | name ----+------- 1 | Paul 2 | Allen 3 | Teddy 4 | Mark 5 | David (5 rows)