基本的なSELECT文

SELECT column1, column2
FROM table_name
WHERE condition
ORDER BY column1 ASC;
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テーブルやカラムの別名を付ける

SELECT column1 AS alias_name
FROM table_name AS t;
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テーブル結合

SELECT t1.column1, t2.column2
FROM table1 t1
JOIN table2 t2 ON t1.id = t2.id
WHERE t1.status = 'active' AND t2.type = 'A';
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IN句で複数条件

SELECT column1
FROM table_name
WHERE column1 IN ('value1', 'value2', 'value3');
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LIKE句（パターン検索）

SELECT *
FROM table_name
WHERE column_name LIKE '%pattern%';
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NULLチェック

SELECT *
FROM table_name
WHERE column_name IS NULL;
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CASE式（条件分岐）

SELECT 
  column1,
  CASE 
    WHEN condition THEN '結果1'
    ELSE '結果2'
  END AS new_column
FROM table_name;
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LIMIT句（取得件数制限）

SELECT *
FROM table_name
LIMIT 10;
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GROUP BY + 集計関数 + HAVING

SELECT category, COUNT(*) AS cnt, SUM(price) AS total_price
FROM table_name
GROUP BY category
HAVING COUNT(*) > 5;
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MIN, MAX, AVGの使用例

SELECT 
  MIN(price) AS min_price,
  MAX(price) AS max_price,
  AVG(price) AS avg_price
FROM table_name;
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データ操作系

INSERT INTO table_name (column1, column2)
VALUES ('value1', 'value2');

UPDATE table_name
SET column1 = 'new_value'
WHERE id = 1;

DELETE FROM table_name
WHERE id = 1;
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テーブル構造変更

ALTER TABLE table_name ADD column_name datatype;

DROP TABLE table_name;
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トランザクション制御

COMMIT;
ROLLBACK;
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CREATE文（テーブル作成例）

CREATE TABLE table_name (
  id INT PRIMARY KEY,
  name VARCHAR(100)
);
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