有条件时添加唯一列

Question

我有table这些是table

的字段

project_labor
PROJECT_NO, LABOR_ID, STATUS

状态字段有两个值（完整或完整）
如果status的值为(complete) labor id可以重复
但如果状态值为（不完整），则 labor id 必须是唯一的

Answer 1

您可以使用函数索引（默认情况下 NULL 跳过单列索引的值）：

CREATE UNIQUE INDEX IX_name 
ON project_labor (CASE WHEN STATUS='complete' THEN NULL ELSE LABOR_ID END);

db<>fiddle demo

完整脚本：

CREATE TABLE project_labor(PROJECT_NO INT, LABOR_ID INT, STATUS VARCHAR2(10));

CREATE UNIQUE INDEX IX_name 
ON project_labor (CASE WHEN STATUS='complete' THEN NULL ELSE labor_id END);

INSERT INTO project_labor(project_no,status,labor_id) VALUES(1, 'uncomplete', 1);
INSERT INTO project_labor(project_no,status,labor_id) VALUES(2, 'uncomplete', 1);
-- ORA-00001: unique constraint (IX_NAME) violated

INSERT INTO project_labor(project_no,status,labor_id) VALUES(3, 'complete', 2)
INSERT INTO project_labor(project_no,status,labor_id) VALUES(4, 'complete', 2)

SELECT * FROM project_labor

它相当于来自其他 RDBMS 的部分索引：

PostgreSQL - partial index / SQLite - Partial index / SQL Server - filtered index

有条件时添加唯一列

Add unique column when I have condition

sql

oracle

unique-index