一文读懂获取GBase 8s数据库表约束与索引列信息

原创 GBASE数据库 2025-04-03

原文链接：https://www.gbase.cn/community/post/5609
更多精彩内容尽在南大通用GBase技术社区，南大通用致力于成为用户最信赖的数据库产品供应商。

今天，我们将探讨如何在南大通用GBase 8s中获取表的约束和索引列信息，为您的数据库管理提供有力的工具。

获取表的约束信息

在数据库设计中，约束是确保数据完整性和一致性的关键。GBase 8s提供了多种约束类型，包括主键、唯一、非空、检查和外键约束。了解这些约束信息，可以帮助我们更好地理解表结构，优化查询性能，并确保数据的准确性。

主键约束（P）：确保表中每一行数据的唯一性，通常用于标识表中的唯一记录。
唯一约束（U）：确保表中某一列或多列的值唯一，但允许为空。
非空约束（N）：确保某一列的值不能为空。
检查约束（C）：确保某一列或多列的值满足特定条件。
外键约束（R）：确保表中某一列或多列的值在另一个表中存在，用于维护表之间的关系。

通过以下SQL语句，我们可以轻松获取表的约束信息：

SELECT t.tabname, c.constrtype, c.constrname
FROM sysconstraints c, systables t
WHERE c.tabid = t.tabid AND tabname = 'xxxx';

示例：

set environment sqlmode 'oracle';

CREATE TABLE department (

    department_id   SERIAL PRIMARY KEY,  -- 主键，自增字段

    department_name VARCHAR(100) NOT NULL UNIQUE -- 部门名称，非空且唯一

);



CREATE TABLE employee (

    employee_id    SERIAL PRIMARY KEY,               -- 主键，自增字段

    first_name     VARCHAR(50) NOT NULL,             -- 非空约束

    email          VARCHAR(100) UNIQUE,              -- 唯一约束 

    salary         DECIMAL(10, 2) CHECK (salary >= 0), -- 检查约束，工资不能为负数

    department_id  INT,                              -- 外键字段

    CONSTRAINT fk_department FOREIGN KEY (department_id) REFERENCES department(department_id) -- 外键约束

);



-- 查询department相关约束信息


SELECT t.tabname, c.constrtype, c.constrname

FROM sysconstraints c, systables t

WHERE c.tabid = t.tabid and tabname = 'department';



TABNAME     department

CONSTRTYPE  P

CONSTRNAME  u1004_20



TABNAME     department

CONSTRTYPE  U

CONSTRNAME  u1004_21



TABNAME     department

CONSTRTYPE  N

CONSTRNAME  n1004_22



TABNAME     department

CONSTRTYPE  N

CONSTRNAME  n1004_23



4 row(s) retrieved.



-- 查询employee相关约束信息

SELECT t.tabname, c.constrtype, c.constrname

FROM sysconstraints c, systables t

WHERE c.tabid = t.tabid and tabname = 'employee';



TABNAME     employee

CONSTRTYPE  P

CONSTRNAME  u1005_24



TABNAME     employee

CONSTRTYPE  U

CONSTRNAME  u1005_25



TABNAME     employee

CONSTRTYPE  R

CONSTRNAME  fk_department



TABNAME     employee

CONSTRTYPE  N

CONSTRNAME  n1005_27



TABNAME     employee

CONSTRTYPE  N

CONSTRNAME  n1005_28



TABNAME     employee

CONSTRTYPE  C

CONSTRNAME  c1005_29



6 row(s) retrieved.

获取索引列信息

索引是数据库中用于提高查询性能的重要工具。通过索引，可以快速定位和检索数据，从而显著提高查询效率。了解索引列信息，可以帮助我们优化查询性能，确保数据库的高效运行。

通过以下SQL语句，我们可以获取表的索引列信息：

SELECT UNIQUE
    t.tabname,
    i.idxname,
    i.idxtype,
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part1),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part2),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part3),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part4),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part5),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part6),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part7),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part8),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part9),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part10),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part11),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part12),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part13),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part14),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part15),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part16)
FROM sysindexes i, systables t
WHERE i.tabid = t.tabid AND tabname = 'xxxx';

示例：

-- 创建索引
CREATE INDEX idx_1 ON department(department_name);

-- 查询department相关索引列信息
SELECT UNIQUE
    t.tabname,
    i.idxname,
    i.idxtype,
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part1),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part2),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part3),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part4),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part5),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part6),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part7),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part8),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part9),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part10),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part11),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part12),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part13),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part14),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part15),
    (SELECT c.colname FROM syscolumns c WHERE c.tabid = i.tabid AND c.colno = i.part16)
FROM sysindexes i, systables t
WHERE i.tabid = t.tabid AND tabname = 'department';

返回结果：

TABNAME       department
IDXNAME        1004_20
IDXTYPE       U
(EXPRESSION)  department_id
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  

TABNAME       department
IDXNAME        1004_21
IDXTYPE       U
(EXPRESSION)  department_name
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)  
(EXPRESSION)

通过本文的介绍，我们希望帮助您更好地理解和使用南大通用GBase 8s数据库，轻松获取表的约束和索引列信息，提高数据库管理的效率和准确性。如果您在使用过程中遇到任何问题或有任何建议，欢迎随时与我们交流，我们将竭诚为您提供支持。

原文链接：https://www.gbase.cn/community/post/5609
更多精彩内容尽在南大通用GBase技术社区，南大通用致力于成为用户最信赖的数据库产品供应商。