SQL（Structured Query Language）是用于管理和操作關(guān)系型數(shù)據(jù)庫的語言。以下是一些常用的SQL語句： 1. **創(chuàng)建表**：用于在數(shù)據(jù)庫中創(chuàng)建新的數(shù)據(jù)表。 ```sql CREATE TABLE table_name ( ??column1 datatype constraints, ??column2 datatype constraints, ??... ); ``` 2. **插入數(shù)據(jù)**：用于向表中插入新的數(shù)據(jù)記錄。 ```sql INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...); ``` 3. **更新數(shù)據(jù)**：用于更新現(xiàn)有數(shù)據(jù)記錄。 ```sql UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition; ``` 4. **刪除數(shù)據(jù)**：用于從表中刪除數(shù)據(jù)記錄。 ```sql DELETE FROM table_name WHERE condition; ``` 5. **選擇數(shù)據(jù)**：用于從表中檢索數(shù)據(jù)記錄。 ```sql SELECT column1, column2, ... FROM table_name WHERE condition; ``` 6. **條件篩選**：用于根據(jù)特定條件對(duì)數(shù)據(jù)進(jìn)行篩選。 ```sql SELECT * FROM table_name WHERE column_name = value; SELECT * FROM table_name WHERE column_name LIKE 'pattern%'; SELECT * FROM table_name WHERE column_name BETWEEN value1 AND value2; ``` 7. **排序數(shù)據(jù)**：用于對(duì)結(jié)果按照特定字段進(jìn)行排序。 ```sql SELECT * FROM table_name ORDER BY column_name ASC/DESC; ``` 8. **聚合函數(shù)**：用于對(duì)數(shù)據(jù)執(zhí)行聚合操作（如求和、平均值等）。 ```sql SELECT COUNT(column_name) FROM table_name; SELECT SUM(column_name) FROM table_name; SELECT AVG(column_name) FROM table_name; SELECT MAX(column_name) FROM table_name; SELECT MIN(column_name) FROM table_name; ``` 9. **分組數(shù)據(jù)**：用于按照特定字段對(duì)數(shù)據(jù)進(jìn)行分組統(tǒng)計(jì)。 ```sql SELECT column1, COUNT(column2) FROM table_name GROUP BY column1; ``` 10. **連接表**：用于將多個(gè)表的數(shù)據(jù)聯(lián)合起來。 ```sql SELECT * FROM table1 INNER JOIN table2 ON table1.column_name = table2.column_name; ``` 11. **創(chuàng)建索引**：用于提高數(shù)據(jù)庫查詢性能。 ```sql CREATE INDEX index_name ON table_name (column_name); ``` 12. **刪除表**：用于從數(shù)據(jù)庫中刪除現(xiàn)有表。 ```sql DROP TABLE table_name; ``` 以上只是SQL語句中的一部分，SQL語言非常豐富，支持更多復(fù)雜的查詢和操作。根據(jù)具體的數(shù)據(jù)庫管理系統(tǒng)，SQL的語法和特性可能會(huì)略有不同，因此建議在實(shí)際使用時(shí)查閱相關(guān)的數(shù)據(jù)庫文檔或教程來了解更多詳細(xì)信息。