SQLite3日期與時間，常見函數

SQLite3日期與時間，常見函數

import sqlite3

#con = sqlite3.connect('example.db')
con = sqlite3.connect(":memory:")

c = con.cursor()

# Create table
c.execute('''CREATE TABLE stocks
             (date text, trans text, symbol text, qty real, price real)''')

# Insert a row of data
c.execute("INSERT INTO stocks VALUES (?,?,?,?,?)", ('2006-03-27','BUY','RHAT',100,60.14))


# Larger example that inserts many records at a time
purchases = [('2006-03-28', 'BUY', 'IBM', 1000, 45.00),
             ('2006-04-05', 'BUY', 'MSFT', 1000, 72.00),
             ('2006-04-06', 'SELL', 'IBM', 500, 53.00),
             ('2006-04-07', 'SELL', 'MSFT', 500, 74.00),
             ('2006-04-08', 'SELL', 'IBM', 500, 54.00),
             ('2006-04-09', 'SELL', 'MSFT', 500, 73.00),
             ('2006-04-10', 'SELL', 'MSFT', 500, 75.00),
             ('2006-04-12', 'SELL', 'IBM', 500, 55.00),
            ]
c.executemany('INSERT INTO stocks VALUES (?,?,?,?,?)', purchases)


# Save (commit) the changes
con.commit()


# Do this instead
t = ('RHAT',)
c.execute('SELECT * FROM stocks WHERE symbol=?', t)
#print(c.fetchone())


#for row in c.execute('SELECT * FROM stocks ORDER BY price'):
#    print(row)
    
    
#for row in c.execute('SELECT * FROM stocks LIMIT 5 OFFSET 0'):
#    print(row)
for row in c.execute('SELECT * FROM stocks LIMIT 5 OFFSET 1'):
    print(row)
#Select Top N * From


# ====================================================================================
# SQLite 日期 & 時間
# ====================================================================================
print('='*30)
print('SQLite 日期 & 時間')
print('='*30)

# 計算當前日期
c.execute("SELECT date('now')")
print(c.fetchone())

# 計算當前月份的最后一天：
c.execute("SELECT date('now','start of month','+1 month','-1 day');")
print(c.fetchone())

# 計算給定 UNIX 時間戳 1092941466 的日期和時間：
c.execute("SELECT datetime(1092941466, 'unixepoch');")
print(c.fetchone())

# 計算給定 UNIX 時間戳 1092941466 相對本地時區的日期和時間：
c.execute("SELECT datetime(1092941466, 'unixepoch', 'localtime');")
print(c.fetchone())

# 計算當前的 UNIX 時間戳：
c.execute("SELECT datetime(1092941466, 'unixepoch', 'localtime');")
print(c.fetchone())

# 計算美國"獨立宣言"簽署以來的天數：
c.execute("SELECT julianday('now') - julianday('1776-07-04');")
print(c.fetchone())

# 計算從 2004 年某一特定時刻以來的秒數：
c.execute("SELECT strftime('%s','now') - strftime('%s','2004-01-01 02:34:56');")
print(c.fetchone())

# 計算當年 10 月的第一個星期二的日期：
c.execute("SELECT date('now','start of year','+9 months','weekday 2');")
print(c.fetchone())

# 計算從 UNIX 紀元算起的以秒為單位的時間（類似 strftime('%s','now') ，不同的是這里有包括小數部分）：
c.execute("SELECT (julianday('now') - 2440587.5)*86400.0;")
print(c.fetchone())

# 在 UTC 與本地時間值之間進行轉換，當格式化日期時，使用 utc 或 localtime 修飾符，如下所示：
c.execute("SELECT time('12:00', 'localtime');")
print(c.fetchone())

# 
c.execute("SELECT time('12:00', 'utc');")
print(c.fetchone())

con.close()

# ====================================================================================
# SQLite 常用函數
# ====================================================================================
print('='*30)
print('SQLite 常用函數')
print('='*30)


con = sqlite3.connect(":memory:")

c = con.cursor()

# Create table
c.execute('''CREATE TABLE COMPANY
            (ID integer, NAME text, AGE integer, ADDRESS text, SALARY real)''')

# Larger example that inserts many records at a time
purchases = [(1,'Paul',32,'California',20000.0),
             (2,'Allen',25,'Texas',15000.0),
             (3,'Teddy',23,'Norway',20000.0),
             (4,'Mark',25,'Rich-Mond',65000.0),
             (5,'David',27,'Texas',85000.0),
             (6,'Kim',22,'South-Hall',45000.0),
             (7,'James',24,'Houston',10000.0)]
c.executemany('INSERT INTO COMPANY VALUES (?,?,?,?,?)', purchases)


# Save (commit) the changes
con.commit()


# 返回數據庫表最后 n 行記錄
# 先計算一個數據庫表中的行數
c.execute("SELECT count(*) FROM COMPANY;")
last = c.fetchone()[0]
n = 5
c.execute("SELECT * FROM COMPANY LIMIT ? OFFSET ?;", (n, last-n))
for row in c:
    print(row)



# 計算一個數據庫表中的行數
c.execute("SELECT count(*) FROM COMPANY;")
print(c.fetchone())

# 選擇某列的最大值
c.execute("SELECT max(salary) FROM COMPANY;")
print(c.fetchone())

# 選擇某列的最小值
c.execute("SELECT min(salary) FROM COMPANY;")
print(c.fetchone())

# 計算某列的平均值
c.execute("SELECT avg(salary) FROM COMPANY;")
print(c.fetchone())

# 為一個數值列計算總和
c.execute("SELECT sum(salary) FROM COMPANY;")
print(c.fetchone())

# 返回一個介於 -9223372036854775808 和 +9223372036854775807 之間的偽隨機整數
c.execute("SELECT random() AS Random;")
print(c.fetchone())

# 返回數值參數的絕對值
c.execute("SELECT abs(5), abs(-15), abs(NULL), abs(0), abs('ABC');")
print(c.fetchone())

# 把字符串轉換為大寫字母
c.execute("SELECT upper(name) FROM COMPANY;")
print(c.fetchone())

# 把字符串轉換為小寫字母
c.execute("SELECT lower(name) FROM COMPANY;")
print(c.fetchone())

# 返回字符串的長度
c.execute("SELECT name, length(name) FROM COMPANY;")
print(c.fetchone())

# 返回 SQLite 庫的版本
c.execute("SELECT sqlite_version() AS 'SQLite Version';")
print(c.fetchone())

# 
c.execute("SELECT CURRENT_TIMESTAMP;")
print(c.fetchone())