在Oracle中，可以靈活運用“exist”關鍵字來查詢是否存在符合條件的記錄。以下是一些技巧：
SELECT *
FROM table_name
WHERE EXISTS (
SELECT 1
FROM another_table
WHERE condition
);
SELECT *
FROM table_name
WHERE NOT EXISTS (
SELECT 1
FROM another_table
WHERE condition
);
SELECT *
FROM table1
WHERE EXISTS (
SELECT 1
FROM table2
WHERE table1.column = table2.column
);
SELECT *
FROM table1
WHERE EXISTS (
SELECT 1
FROM table2
WHERE table1.column = table2.column
AND table2.another_column = 'value'
);
通過靈活運用“exist”關鍵字，可以更加靈活地查詢符合條件的記錄，實現更加復雜的查詢需求。
