import unittest
import psycopg2
import pandas as pd
import re

class TestPostgresQuery(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        cls.connection = psycopg2.connect(
            host="localhost",
            user="agent",
            password="qwerty",
            dbname="testdb",
            sslmode="disable"
        )
        cls.cursor = cls.connection.cursor()

    def test_all_rows_selected(self):
        """Check if query selects all rows from products table."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute("SELECT COUNT(*) FROM products;")
        expected_count = self.cursor.fetchone()[0]
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        _dynamic_test(
            self,
            len(rows) == expected_count,
            "Query selects all rows from products table.",
            f"Query does not select all rows. Expected {expected_count}, got {len(rows)}."
        )

    def test_column_names(self):
        """Check if output includes the required columns."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        actual_columns = [desc[0] for desc in self.cursor.description]
        required_columns = {"product_id", "product_name"}
        # Look for a column that is uppercase and one that is substring
        has_upper = any("upper" in col or "upper" in normalize_text(col) for col in actual_columns)
        has_first3 = any("first3" in col or "first3" in normalize_text(col) for col in actual_columns)
        condition = required_columns.issubset(set(actual_columns)) and has_upper and has_first3
        _dynamic_test(
            self,
            condition,
            "Output includes all required columns.",
            "Output does not include all required columns: product_id, product_name, uppercase and first 3 letters columns."
        )

    def test_uppercase_column(self):
        """Check if the uppercase column displays product names in all capital letters."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        columns = [desc[0] for desc in self.cursor.description]
        # Find the uppercase column
        upper_col_idx = None
        for idx, col in enumerate(columns):
            if "upper" in col or "upper" in normalize_text(col):
                upper_col_idx = idx
                break
        self.cursor.execute("SELECT product_name FROM products;")
        product_names = [row[0] for row in self.cursor.fetchall()]
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        # Find matching uppercase values
        condition = True
        for i, row in enumerate(rows):
            if upper_col_idx is not None:
                expected = product_names[i].upper()
                actual = row[upper_col_idx]
                if actual != expected:
                    condition = False
                    break
        _dynamic_test(
            self,
            condition,
            "Uppercase column displays product names in all capital letters.",
            "Uppercase column does not display all product names in uppercase."
        )

    def test_first3_column(self):
        """Check if the first 3 letters column displays only the first three characters of each product name."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        columns = [desc[0] for desc in self.cursor.description]
        # Find the first3 column
        first3_col_idx = None
        for idx, col in enumerate(columns):
            if "first3" in col or "first3" in normalize_text(col):
                first3_col_idx = idx
                break
        self.cursor.execute("SELECT product_name FROM products;")
        product_names = [row[0] for row in self.cursor.fetchall()]
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        condition = True
        for i, row in enumerate(rows):
            if first3_col_idx is not None:
                expected = product_names[i][:3]
                actual = row[first3_col_idx]
                if actual != expected:
                    condition = False
                    break
        _dynamic_test(
            self,
            condition,
            "First 3 letters column displays correct substring for all products.",
            "First 3 letters column does not display correct substring for all products."
        )


def _dynamic_test(test_case, condition, success_message, failure_message):
    if condition:
        test_case._testMethodName = success_message
        test_case.assertTrue(True, success_message)
    else:
        test_case._testMethodName = failure_message
        test_case.fail(failure_message)

def normalize_text(text):
    text = text.lower()
    text = re.sub(r"\s{2,}", " ", text)
    text = re.sub(r"\s*([,:?])\s*", r"\1 ", text)
    return text.strip()

if __name__ == "__main__":
    unittest.main()


test_solution.py

実践的なデータ分析スキルに焦点を当て、SQLを基礎から学べる包括的で初心者向けのコースです。分かりやすい解説、実際の事例、実践的な課題を通じて、SQLを用いたデータのクエリ、変換、分析を習得します。

リレーショナルデータベースとSQLの基礎概念を学習します。テーブルからデータを取得、フィルタリング、並べ替える方法を探求し、より高度なデータ分析の基礎を築きます。

SQLの強力な集計機能を深く学びます。データを要約し、グループ化し、より深い洞察のために分析する方法を習得します。

複数のテーブルからデータを組み合わせる力を引き出します。さまざまな種類の結合を実行し、複雑なビジネス上の質問に答える方法を学びます。

サブクエリ、ウィンドウ関数、データ変換などを含む高度なSQL技術を習得し、強力なデータ分析を実現します。

チャレンジ：商品名のフォーマット

解答