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52 lines
1.7 KiB
Python
52 lines
1.7 KiB
Python
# Sebastian Raschka, 2014
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# Selecting rows from an existing SQLite database
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import sqlite3
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sqlite_file = 'my_first_db.sqlite' # name of the sqlite database file
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table_name = 'my_table_2' # name of the table to be queried
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id_column = 'my_1st_column'
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some_id = 123456
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column_2 = 'my_2nd_column'
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column_3 = 'my_3rd_column'
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# Connecting to the database file
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conn = sqlite3.connect(sqlite_file)
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c = conn.cursor()
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# 1) Contents of all columns for row that match a certain value in 1 column
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c.execute('SELECT * FROM {tn} WHERE {cn}="Hi World"'.\
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format(tn=table_name, cn=column_2))
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all_rows = c.fetchall()
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print('1):', all_rows)
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# 2) Value of a particular column for rows that match a certain value in column_1
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c.execute('SELECT ({coi}) FROM {tn} WHERE {cn}="Hi World"'.\
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format(coi=column_2, tn=table_name, cn=column_2))
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all_rows = c.fetchall()
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print('2):', all_rows)
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# 3) Value of 2 particular columns for rows that match a certain value in 1 column
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c.execute('SELECT {coi1},{coi2} FROM {tn} WHERE {coi1}="Hi World"'.\
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format(coi1=column_2, coi2=column_3, tn=table_name, cn=column_2))
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all_rows = c.fetchall()
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print('3):', all_rows)
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# 4) Selecting only up to 10 rows that match a certain value in 1 column
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c.execute('SELECT * FROM {tn} WHERE {cn}="Hi World" LIMIT 10'.\
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format(tn=table_name, cn=column_2))
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ten_rows = c.fetchall()
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print('4):', ten_rows)
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# 5) Check if a certain ID exists and print its column contents
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c.execute("SELECT * FROM {tn} WHERE {idf}=?".\
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format(tn=table_name, cn=column_2, idf=id_column), (123456,))
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id_exists = c.fetchone()
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if id_exists:
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print('5): {}'.format(id_exists))
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else:
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print('5): {} does not exist'.format(some_id))
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# Closing the connection to the database file
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conn.close()
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