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  • SQLite3日期与时间,常见函数

    SQLite3日期与时间,常见函数

    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 & 时间
    # ====================================================================================
    print('='*30)
    print('SQLite 日期 & 时间')
    print('='*30)
    
    # 计算当前日期
    c.execute("SELECT date('now')")
    print(c.fetchone())
    
    # 计算当前月份的最后一天:
    c.execute("SELECT date('now','start of month','+1 month','-1 day');")
    print(c.fetchone())
    
    # 计算给定 UNIX 时间戳 1092941466 的日期和时间:
    c.execute("SELECT datetime(1092941466, 'unixepoch');")
    print(c.fetchone())
    
    # 计算给定 UNIX 时间戳 1092941466 相对本地时区的日期和时间:
    c.execute("SELECT datetime(1092941466, 'unixepoch', 'localtime');")
    print(c.fetchone())
    
    # 计算当前的 UNIX 时间戳:
    c.execute("SELECT datetime(1092941466, 'unixepoch', 'localtime');")
    print(c.fetchone())
    
    # 计算美国"独立宣言"签署以来的天数:
    c.execute("SELECT julianday('now') - julianday('1776-07-04');")
    print(c.fetchone())
    
    # 计算从 2004 年某一特定时刻以来的秒数:
    c.execute("SELECT strftime('%s','now') - strftime('%s','2004-01-01 02:34:56');")
    print(c.fetchone())
    
    # 计算当年 10 月的第一个星期二的日期:
    c.execute("SELECT date('now','start of year','+9 months','weekday 2');")
    print(c.fetchone())
    
    # 计算从 UNIX 纪元算起的以秒为单位的时间(类似 strftime('%s','now') ,不同的是这里有包括小数部分):
    c.execute("SELECT (julianday('now') - 2440587.5)*86400.0;")
    print(c.fetchone())
    
    # 在 UTC 与本地时间值之间进行转换,当格式化日期时,使用 utc 或 localtime 修饰符,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 常用函数
    # ====================================================================================
    print('='*30)
    print('SQLite 常用函数')
    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()
    
    # 返回数据库表最后 n 行记录
    # 先计算一个数据库表中的行数 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)

    # 计算一个数据库表中的行数 c.execute("SELECT count(*) FROM COMPANY;") print(c.fetchone()) # 选择某列的最大值 c.execute("SELECT max(salary) FROM COMPANY;") print(c.fetchone()) # 选择某列的最小值 c.execute("SELECT min(salary) FROM COMPANY;") print(c.fetchone()) # 计算某列的平均值 c.execute("SELECT avg(salary) FROM COMPANY;") print(c.fetchone()) # 为一个数值列计算总和 c.execute("SELECT sum(salary) FROM COMPANY;") print(c.fetchone()) # 返回一个介于 -9223372036854775808 和 +9223372036854775807 之间的伪随机整数 c.execute("SELECT random() AS Random;") print(c.fetchone()) # 返回数值参数的绝对值 c.execute("SELECT abs(5), abs(-15), abs(NULL), abs(0), abs('ABC');") print(c.fetchone()) # 把字符串转换为大写字母 c.execute("SELECT upper(name) FROM COMPANY;") print(c.fetchone()) # 把字符串转换为小写字母 c.execute("SELECT lower(name) FROM COMPANY;") print(c.fetchone()) # 返回字符串的长度 c.execute("SELECT name, length(name) FROM COMPANY;") print(c.fetchone()) # 返回 SQLite 库的版本 c.execute("SELECT sqlite_version() AS 'SQLite Version';") print(c.fetchone()) # c.execute("SELECT CURRENT_TIMESTAMP;") print(c.fetchone())
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  • 原文地址:https://www.cnblogs.com/hhh5460/p/5206001.html
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