MySQL 的保留字（或关键字）是在 SQL 语句中有特殊意义的单词。当你为表或列命名时，建议避免使用这些关键字，否则可能会导致查询错误或意外的行为。
以下是 MySQL 8.0 中的部分保留字（注意，这不是一个完整的列表）：
ADD ALL ALTER ANALYZE AND AS ASC ASENSITIVE BEFORE BETWEEN BIGINT BINARY BLOB BOTH BY CALL CASCADE CASE CHANGE CHAR CHARACTER CHECK COLLATE COLUMN CONDITION CONSTRAINT CONTINUE CONVERT CREATE CROSS CURRENT_DATE CURRENT_TIME CURRENT_TIMESTAMP CURRENT_USER CURSOR DATABASE DATABASES DAY_HOUR DAY_MICROSECOND DAY_MINUTE DAY_SECOND DEC DECIMAL DECLARE DEFAULT DELAYED DELETE DESC DESCRIBE DETERMINISTIC DISTINCT DISTINCTROW DIV DOUBLE DROP DUAL EACH ELSE ELSEIF ENCLOSED ESCAPED EXCEPT EXISTS EXIT EXPLAIN FALSE FETCH FLOAT FLOAT4 FLOAT8 FOR FORCE FOREIGN FROM FULLTEXT GENERATED GET GRANT GROUP HAVING HIGH_PRIORITY HOUR_MICROSECOND HOUR_MINUTE HOUR_SECOND IF IGNORE IN INDEX INFILE INNER INOUT INSENSITIVE INSERT INT INT1 INT2 INT3 INT4 INT8 INTEGER INTERVAL INTO IS ITERATE JOIN KEY KEYS KILL LEADING LEAVE LEFT LIKE LIMIT LINEAR LINES LOAD LOCALTIME LOCALTIMESTAMP LOCK LONG LONGBLOB LONGTEXT LOOP LOW_PRIORITY MASTER_BIND MASTER_SSL_VERIFY_SERVER_CERT MATCH MAXVALUE MEDIUMBLOB MEDIUMINT MEDIUMTEXT MIDDLEINT MINUTE_MICROSECOND MINUTE_SECOND MOD MODIFIES NATURAL NOT NO_WRITE_TO_BINLOG NULL NUMERIC ON OPTIMIZE OPTIMIZER_COSTS OPTION OPTIONALLY OR ORDER OUT OUTER OUTFILE PARTITION PRECISION PRIMARY PROCEDURE PURGE RANGE READ READS REAL REFERENCES REGEXP RELEASE RENAME REPEAT REPLACE REQUIRE RESIGNAL RESTRICT RETURN REVOKE RIGHT RLIKE ROW ROWS ROW_FORMAT SCHEMA SCHEMAS SECOND_MICROSECOND SELECT SENSITIVE SEPARATOR SET SHOW SIGNAL SMALLINT SPATIAL SPECIFIC SQL SQLEXCEPTION SQLSTATE SQLWARNING SQL_BIG_RESULT SQL_CALC_FOUND_ROWS SQL_SMALL_RESULT SSL STARTING STORED STRAIGHT_JOIN SYSTEM TABLE TERMINATED THEN TINYBLOB TINYINT TINYTEXT TO TRAILING TRIGGER TRUE UNDO UNION UNIQUE UNLOCK UNSIGNED UPDATE USAGE USE USING UTC_DATE UTC_TIME UTC_TIMESTAMP VALUES VARBINARY VARCHAR VARCHARACTER VARYING VIRTUAL WHEN WHERE WHILE WITH WRITE XOR YEAR_MONTH ZEROFILL
如果你必须使用这些保留字作为列或表的名称，应该用反引号 (`) 将它们括起来。
就像下面这个sql一样的写法。
SELECT `key` FROM users;
但最好的实践还是避免使用这些关键字。
