數據類型
- 數值數據類型
- integer 存儲整數。使用這個類型可存儲典型的整數 4字節 -2147483648 至 +2147483647
- double 可變精度，不精確 8字節 15位數字精度
- serial 自動遞增整數 4字節 1 至 2147483647
- 字符串數據類型
- character varying(size) 這里size是要存儲的字符數。 可變長度字符串。
- text 可變長度字符串。
- 日期/時間數據類型
- timestamp(6) without time zone
- date 日期(沒有時間) 4字節 4713 bc 5874897 ad 1微秒/14位數
- 其他數據類型
- boolean 它指定true或false的狀態。 1字節
- money 貨幣金額 8字節 -92233720368547758.08 至 +92233720368547758.07
創建表
CREATE TABLE eric_staff(
name character varying NOT NULL,
sex character varying,
birthy date,
CONSTRAINT eric_staff_pkey PRIMARY KEY (name)
)
WITH(
OIDS=FALSE
);
ALTER TABLE eric_staff OWNER TO postgres;
創建模式（架構）
CREATE SCHEMA
創建表
CREATE TABLE table_name()
刪除表
DROP TABLE table_name
INSERT
INSERT INTO eric.eric_staff(name,sex,birthy)VALUES
('eric','man','2017-10-01'),
('jane','women','2017-10-03'),
('moon','women','2017-10-02');
SELECT
SELECT (name) FROM eric.eric_staff WHERE birthy = '2017-10-01';
UPDATE
UPDATE eric.eric_staff SET birthy = '1991.10.12' WHERE name = 'eric';
DELETE
DELETE FROM eric.eric_staff WHERE name = 'moon';
ORDER BY
SELECT column-list
FROM table_name
[WHERE condition]
[ORDER BY column1, column2, .. columnN] [ASC | DESC];
ASC--結果按升序排列
DESC--結果按降序排列
SELECT * FROM eric.eric_staff ORDER BY birthy DESC;
GROUP BY
INSERT INTO eric.eric_staff(
name, sex, birthy, money)
VALUES ('eric', 'man', '2017-10-12', 12.3),
('jane', 'women', '2017-10-11', 13.2),
('frank', 'man', '2017-10-12', 5),
('eric', 'man', '2017-10-15', 23),
('eric', 'man', '2017-10-10', 13.3);
SELECT name, SUM(money)
FROM eric.eric_staff GROUP BY name;
微信截圖_20171116213514.png
HAVING
SELECT name FROM eric.eric_staff GROUP BY name HAVING count(name)>1;
# 選出name字段出現一次以上的數據
WHERE
SELECT * FROM eric.eric_staff WHERE (NAME = 'eric' AND NAME = 'jane') OR MONEY = '13.3';
# 篩選出名字為eric的數據
SELECT * FROM eric.eric_staff WHERE money NOT IN('13.0', '5.0');
# 選出數值不在數組范圍內的數據
SELECT * FROM eric.eric_staff WHERE name LIKE '%e%';
# 選出name中含有e的數據
SELECT * FROM eric.eric_staff WHERE money BETWEEN '6' AND '14';
# 選出錢數在6到14范圍之間的數據
連接
- 內連接（簡單連接）
# 選出兩個表中name sex一樣的數據
SELECT eric.eric_staff.name, eric.eric_staff.sex, eric.eric_other.name, eric.eric_other.sex
FROM eric.eric_other
INNER JOIN eric.eric_staff
ON eric.eric_staff.sex = eric.eric_other.sex AND eric.eric_staff.name = eric.eric_other.name;
- 左連接
# 以FROM表為基礎全部顯示，另一張表只顯示匹配項。
SELECT eric.eric_staff.name, eric.eric_staff.sex, eric.eric_other.name, eric.eric_other.sex
FROM eric.eric_other
LEFT OUTER JOIN eric.eric_staff
ON eric.eric_staff.name = eric.eric_other.name;
圖片.png
- 右連接
# 以另一張表為基礎，FROM表只顯示匹配項
SELECT eric.eric_staff.name, eric.eric_staff.sex, eric.eric_other.name, eric.eric_other.sex
FROM eric.eric_other
RIGHT OUTER JOIN eric.eric_staff
ON eric.eric_staff.name = eric.eric_other.name;
圖片.png
- 全外連接
# 左右表全顯示，不匹配的留空。
SELECT eric.eric_staff.name, eric.eric_staff.sex, eric.eric_other.name, eric.eric_other.sex
FROM eric.eric_other
FULL OUTER JOIN eric.eric_staff
ON eric.eric_staff.name = eric.eric_other.name;
圖片.png
創建視圖
- 其實就是將操作后的結果生成一張表，下面兩條語句結果一樣
CREATE OR REPLACE VIEW eric.view_table AS
SELECT eric_other.name,
eric_other.sex
FROM eric.eric_other;
SELECT eric_other.name,
eric_other.sex
FROM eric.eric_other;
- 刪除視圖
DROP VIEW view_table;
python 連接postgresql數據庫
import psycopg2
conn = psycopg2.connect(database="test_db", user="postgres", password="tuji2013", host="127.0.0.1", port="5432")
print ("Opened database successfully")
import psycopg2
conn = psycopg2.connect(database="test_db", user="postgres", password="tuji2013", host="127.0.0.1", port="5432")
cur = conn.cursor()
cur.execute("INSERT INTO eric.eric_staff (name, sex, birthy, money) VALUES ('test_python', 'man', '2017-11-19', '12')")
conn.commit()#提交事務
print('插入成功')
