PostgreSQL數據庫平常學習筆記8-NOT,LIKE

先學習NOT（邏輯非）用法。

#查詢StudentBirthday非空列
SELECT * FROM "public"."Students" WHERE "StudentBirthday" IS NOT NULL;
#注意對比兩個語句查詢結果
SELECT "StudentBirthday" FROM "public"."Students" WHERE "StudentBirthday" IS NOT NULL;

排除非條件值

#不查詢StudentSalary=2值
SELECT * FROM "public"."Students" WHERE "StudentSalary" NOT IN('2');
#對比查詢語句
SELECT "StudentName","StudentAddress" FROM "public"."Students" WHERE "StudentSalary" NOT IN('2');

LIKE支持模糊查詢，LIKE與兩個通配符（%與_）一塊兒使用，百分號表示零個，一個或多個字符。下劃線表明一個單一字符。通配符能夠被組合使用。ILIKE和LIKE 相似，LIKE區分大小寫，ILIKE不區分。SIMILAR TO和LIKE有類似性，不事後者支持模糊查詢同時還支持正則表達式。

先插入兩條數據用於練習。

INSERT INTO "Students" VALUES (13, '杜牧', '0803-1-1', '陝西省西安市', 3);
INSERT INTO "Students" VALUES (14, '李商隱', '0817-1-1', NULL, NULL);

#查詢全部杜姓人名，匹配單個字符
SELECT * FROM "public"."Students" WHERE "StudentName" LIKE '杜_';
#匹配多個字符，本例匹配StudentAddress列中含有陝西查詢結果
SELECT "StudentName","StudentAddress" FROM "public"."Students" WHERE "StudentAddress" LIKE '%陝西%';