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46 lines
1.1 KiB
Python
46 lines
1.1 KiB
Python
# Example taken from https://www.sqlite.org/windowfunctions.html#udfwinfunc
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import sqlite3
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class WindowSumInt:
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def __init__(self):
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self.count = 0
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def step(self, value):
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"""Adds a row to the current window."""
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self.count += value
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def value(self):
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"""Returns the current value of the aggregate."""
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return self.count
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def inverse(self, value):
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"""Removes a row from the current window."""
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self.count -= value
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def finalize(self):
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"""Returns the final value of the aggregate.
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Any clean-up actions should be placed here.
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"""
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return self.count
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con = sqlite3.connect(":memory:")
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cur = con.execute("create table test(x, y)")
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values = [
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("a", 4),
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("b", 5),
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("c", 3),
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("d", 8),
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("e", 1),
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]
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cur.executemany("insert into test values(?, ?)", values)
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con.create_window_function("sumint", 1, WindowSumInt)
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cur.execute("""
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select x, sumint(y) over (
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order by x rows between 1 preceding and 1 following
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) as sum_y
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from test order by x
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""")
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print(cur.fetchall())
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