[英]What is happening when you run the query “SELECT * FROM table_name WHERE column_name;”?
我有一個包含幾列的數據庫表。 其中一列旨在用作TINYINT（1）DEFAULT 0的布爾設置。
我不小心發現，如果您運行此查詢
SELECT * FROM table_name WHERE column_name;
它返回column_name = 1的行。
我很好奇知道MySql用於處理此查詢的邏輯。
正如文檔在“選擇語法”中所述（（ http://dev.mysql.com/doc/refman/5.1/en/select.html ）
where_condition是一個表達式，對於要選擇的每一行，其值為true
因此，將簡單列名評估為布爾值，並選擇相應的行。 您會發現它也適用於int。
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