CodePattern/13 计算设备/存储/数据库/tf-26.py

import sqlite3, os.path
from cppy.cp_util import testfilepath,db_filename,extract_file_words


# 数据库表结构
TABLES = {
    'documents': '''CREATE TABLE IF NOT EXISTS documents (
                        id INTEGER PRIMARY KEY AUTOINCREMENT,
                        name TEXT NOT NULL
                    )''',
    'words': '''CREATE TABLE IF NOT EXISTS words (
                    doc_id INTEGER NOT NULL,
                    value TEXT NOT NULL,
                    FOREIGN KEY (doc_id) REFERENCES documents (id)
                )''',
    'characters': '''CREATE TABLE IF NOT EXISTS characters (
                        word_id INTEGER NOT NULL,
                        value TEXT NOT NULL,
                        FOREIGN KEY (word_id) REFERENCES words (id)
                )'''
}


# 创建数据库表
def create_db_schema(connection):
    for table, sql in TABLES.items():
        c = connection.cursor()
        c.execute(sql)
        connection.commit()
        c.close()


def load_file_into_database(path_to_file, connection):        
    words = extract_file_words( path_to_file )

    c = connection.cursor()
    c.execute("INSERT INTO documents (name) VALUES (?)", (path_to_file,))
    doc_id = c.lastrowid

    for w in words:
        c.execute("INSERT INTO words (doc_id, value) VALUES (?, ?)", (doc_id, w))
        word_id = c.lastrowid
        for char in w:
            c.execute("INSERT INTO characters (word_id, value) VALUES (?, ?)", (word_id, char))
    connection.commit()
    c.close()

#######################################################
# 建数据库，处理数据入库
#######################################################

# 构造数据库文件的完整路径  
current_dir = os.path.dirname(os.path.abspath(__file__))   
db_file_path = os.path.join(current_dir, db_filename)    

if os.path.exists(db_file_path):          
    os.remove(db_file_path)   

if not os.path.isfile(db_file_path):
    with sqlite3.connect(db_file_path) as connection:
        create_db_schema(connection)
        load_file_into_database(testfilepath, connection)


# 查询输出
with sqlite3.connect(db_file_path) as connection:
    c = connection.cursor()
    c.execute("SELECT value, COUNT(*) as C FROM words GROUP BY value ORDER BY C DESC LIMIT 10")
    for row in c.fetchall():
        print(row[0], '-', row[1])