前言
MySQL和Oracle的關鍵字還是不盡相同的，在Oracle數據庫中，我們的數據表中定義了大量的code字段用來表示主鍵，但是在MySQL中code是關鍵字，使用以前的處理方法就有些“水土不服”。
下面我們來了解一下MySQL中的關鍵字和保留字。
什麼是關鍵字和保留字
關鍵字是指在SQL中有意義的字。 某些關鍵字（例如SELECT，DELETE或BIGINT）是保留的，需要特殊處理才能用作表和列名稱等標識符。 這一點對於內置函數的名稱也適用。
如何使用關鍵字和保留字
非保留關鍵字允許作為標識符，不需要加引號。 如果您要適用保留字作為標識符，就必須適用引號。
舉個例子，BEGIN和END是關鍵字，但不是保留字，因此它們用作標識符不需要引號。 INTERVAL是保留關鍵字，必須加上引號才能用作標識符。
mysql> mysql> use hoegh; Database changed mysql> mysql> CREATE TABLE interval (begin INT, end INT); ERROR 1064 (42000): mysql> mysql> CREATE TABLE `interval` (begin INT, end INT); Query OK, 0 rows affected (0.42 sec) mysql> mysql> show create table `interval`; +----------+--------------------------------------------------------- | Table | Create Table +----------+--------------------------------------------------------- | interval | CREATE TABLE `interval` ( `begin` int(11) DEFAULT NULL, `end` int(11) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1 | +----------+--------------------------------------------------------- 1 row in set (0.00 sec) mysql>
我們看到，第一條語句中表名使用了保留字interval，執行失敗；
第二條語句對interval加了引號，執行成功。
在這裡需要注意的是，引號必須是反引號，而非單引號。否則會報錯，如下所示：
mysql> mysql> drop table `interval`;--使用反引號 Query OK, 0 rows affected (0.11 sec) mysql> mysql> create table 'interval' (begin INT, end INT);--使用單引號，報錯 ERROR 1064 (42000): mysql>
有一個例外
如果標識符在限定名稱（數據庫名）的句點之後，即使是保留關鍵字也不需要引號。
我們以hoegh數據庫為例，如果表名寫為hoegh.interval就不需要對保留字interval加引號了。
mysql> mysql> create table hoegh.interval (begin INT, end INT); Query OK, 0 rows affected (0.19 sec) mysql> mysql> show create table hoegh.interval; +----------+--------------------------------------------------------- | Table | Create Table +----------+--------------------------------------------------------- | interval | CREATE TABLE `interval` ( `begin` int(11) DEFAULT NULL, `end` int(11) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1 | +----------+--------------------------------------------------------- 1 row in set (0.00 sec) mysql>
關於使用內置函數名稱
允許內置函數的名稱可以作為標識符，但最好謹慎使用。例如，COUNT作為列名稱是合法的。但是，默認情況下，在函數名和後面的（之間的函數調用中不允許有空格。這個限制使解析器能夠區分名稱是用於函數調用還是用在非函數上下文中。
附錄
在某些時候，您可能需要升級到更高版本，因此最好查看一下未來的保留字。您可以在涵蓋更高版本的MySQL的手冊中找到這些。對於表中的大多數保留字，在標准SQL中禁止作為列或表的名稱（例如，GROUP）。其中一些保留字，是由於MySQL需要它們並使用一個yacc解析器。
以下列出三張表格：
第一個表格10.2顯示MySQL 5.7中的關鍵字和保留字。保留的關鍵字標記為（R）。此外，_FILENAME是保留的。
第二個表格10.3顯示MySQL 5.7相比5.6版本新增的保留字。
第三個表格10.4顯示MySQL 5.7相比5.6版本刪除的保留字。
Table 10.2 Keywords and Reserved Words in MySQL 5.7
ACCESSIBLE (R) ACCOUNT[a] ACTION ADD (R) AFTER AGAINST AGGREGATE ALGORITHM ALL (R) ALTER (R) ALWAYS[b] ANALYSE ANALYZE (R) AND (R) ANY AS (R) ASC (R) ASCII ASENSITIVE (R) AT AUTOEXTEND_SIZE AUTO_INCREMENT AVG AVG_ROW_LENGTH BACKUP BEFORE (R) BEGIN BETWEEN (R) BIGINT (R) BINARY (R) BINLOG BIT BLOB (R) BLOCK BOOL BOOLEAN BOTH (R) BTREE BY (R) BYTE CACHE CALL (R) CASCADE (R) CASCADED CASE (R) CATALOG_NAME CHAIN CHANGE (R) CHANGED CHANNEL[c] CHAR (R) CHARACTER (R) CHARSET CHECK (R) CHECKSUM CIPHER CLASS_ORIGIN CLIENT CLOSE COALESCE CODE COLLATE (R) COLLATION COLUMN (R) COLUMNS COLUMN_FORMAT COLUMN_NAME COMMENT COMMIT COMMITTED COMPACT COMPLETION COMPRESSED COMPRESSION[d] CONCURRENT CONDITION (R) CONNECTION CONSISTENT CONSTRAINT (R) CONSTRAINT_CATALOG CONSTRAINT_NAME CONSTRAINT_SCHEMA CONTAINS CONTEXT CONTINUE (R) CONVERT (R) CPU CREATE (R) CROSS (R) CUBE CURRENT CURRENT_DATE (R) CURRENT_TIME (R) CURRENT_TIMESTAMP (R) CURRENT_USER (R) CURSOR (R) CURSOR_NAME DATA DATABASE (R) DATABASES (R) DATAFILE DATE DATETIME DAY DAY_HOUR (R) DAY_MICROSECOND (R) DAY_MINUTE (R) DAY_SECOND (R) DEALLOCATE DEC (R) DECIMAL (R) DECLARE (R) DEFAULT (R) DEFAULT_AUTH DEFINER DELAYED (R) DELAY_KEY_WRITE DELETE (R) DESC (R) DESCRIBE (R) DES_KEY_FILE DETERMINISTIC (R) DIAGNOSTICS DIRECTORY DISABLE DISCARD DISK DISTINCT (R) DISTINCTROW (R) DIV (R) DO DOUBLE (R) DROP (R) DUAL (R) DUMPFILE DUPLICATE DYNAMIC EACH (R) ELSE (R) ELSEIF (R) ENABLE ENCLOSED (R) ENCRYPTION[e] END ENDS ENGINE ENGINES ENUM ERROR ERRORS ESCAPE ESCAPED (R) EVENT EVENTS EVERY EXCHANGE EXECUTE EXISTS (R) EXIT (R) EXPANSION EXPIRE EXPLAIN (R) EXPORT EXTENDED EXTENT_SIZE FALSE (R) FAST FAULTS FETCH (R) FIELDS FILE FILE_BLOCK_SIZE[f] FILTER[g] FIRST FIXED FLOAT (R) FLOAT4 (R) FLOAT8 (R) FLUSH FOLLOWS[h] FOR (R) FORCE (R) FOREIGN (R) FORMAT FOUND FROM (R) FULL FULLTEXT (R) FUNCTION GENERAL GENERATED[i] (R) GEOMETRY GEOMETRYCOLLECTION GET (R) GET_FORMAT GLOBAL GRANT (R) GRANTS GROUP (R) GROUP_REPLICATION[j] HANDLER HASH HAVING (R) HELP HIGH_PRIORITY (R) HOST HOSTS HOUR HOUR_MICROSECOND (R) HOUR_MINUTE (R) HOUR_SECOND (R) IDENTIFIED IF (R) IGNORE (R) IGNORE_SERVER_IDS IMPORT IN (R) INDEX (R) INDEXES INFILE (R) INITIAL_SIZE INNER (R) INOUT (R) INSENSITIVE (R) INSERT (R) INSERT_METHOD INSTALL INSTANCE[k] INT (R) INT1 (R) INT2 (R) INT3 (R) INT4 (R) INT8 (R) INTEGER (R) INTERVAL (R) INTO (R) INVOKER IO IO_AFTER_GTIDS (R) IO_BEFORE_GTIDS (R) IO_THREAD IPC IS (R) ISOLATION ISSUER ITERATE (R) JOIN (R) JSON[l] KEY (R) KEYS (R) KEY_BLOCK_SIZE KILL (R) LANGUAGE LAST LEADING (R) LEAVE (R) LEAVES LEFT (R) LESS LEVEL LIKE (R) LIMIT (R) LINEAR (R) LINES (R) LINESTRING LIST LOAD (R) LOCAL LOCALTIME (R) LOCALTIMESTAMP (R) LOCK (R) LOCKS LOGFILE LOGS LONG (R) LONGBLOB (R) LONGTEXT (R) LOOP (R) LOW_PRIORITY (R) MASTER MASTER_AUTO_POSITION MASTER_BIND (R) MASTER_CONNECT_RETRY MASTER_DELAY MASTER_HEARTBEAT_PERIOD MASTER_HOST MASTER_LOG_FILE MASTER_LOG_POS MASTER_PASSWORD MASTER_PORT MASTER_RETRY_COUNT MASTER_SERVER_ID MASTER_SSL MASTER_SSL_CA MASTER_SSL_CAPATH MASTER_SSL_CERT MASTER_SSL_CIPHER MASTER_SSL_CRL MASTER_SSL_CRLPATH MASTER_SSL_KEY MASTER_SSL_VERIFY_SERVER_CERT(R) MASTER_TLS_VERSION[m] MASTER_USER MATCH (R) MAXVALUE (R) MAX_CONNECTIONS_PER_HOUR MAX_QUERIES_PER_HOUR MAX_ROWS MAX_SIZE MAX_STATEMENT_TIME[n] MAX_UPDATES_PER_HOUR MAX_USER_CONNECTIONS MEDIUM MEDIUMBLOB (R) MEDIUMINT (R) MEDIUMTEXT (R) MEMORY MERGE MESSAGE_TEXT MICROSECOND MIDDLEINT (R) MIGRATE MINUTE MINUTE_MICROSECOND (R) MINUTE_SECOND (R) MIN_ROWS MOD (R) MODE MODIFIES (R) MODIFY MONTH MULTILINESTRING MULTIPOINT MULTIPOLYGON MUTEX MYSQL_ERRNO NAME NAMES NATIONAL NATURAL (R) NCHAR NDB NDBCLUSTER NEVER[o] NEW NEXT NO NODEGROUP NONBLOCKING[p] NONE NOT (R) NO_WAIT NO_WRITE_TO_BINLOG (R) NULL (R) NUMBER NUMERIC (R) NVARCHAR OFFSET OLD_PASSWORD[q] ON (R) ONE ONLY OPEN OPTIMIZE (R) OPTIMIZER_COSTS[r] (R) OPTION (R) OPTIONALLY (R) OPTIONS OR (R) ORDER (R) OUT (R) OUTER (R) OUTFILE (R) OWNER PACK_KEYS PAGE PARSER PARSE_GCOL_EXPR[s] PARTIAL PARTITION (R) PARTITIONING PARTITIONS PASSWORD PHASE PLUGIN PLUGINS PLUGIN_DIR POINT POLYGON PORT PRECEDES[t] PRECISION (R) PREPARE PRESERVE PREV PRIMARY (R) PRIVILEGES PROCEDURE (R) PROCESSLIST PROFILE PROFILES PROXY PURGE (R) QUARTER QUERY QUICK RANGE (R) READ (R) READS (R) READ_ONLY READ_WRITE (R) REAL (R) REBUILD RECOVER REDOFILE REDO_BUFFER_SIZE REDUNDANT REFERENCES (R) REGEXP (R) RELAY RELAYLOG RELAY_LOG_FILE RELAY_LOG_POS RELAY_THREAD RELEASE (R) RELOAD REMOVE RENAME (R) REORGANIZE REPAIR REPEAT (R) REPEATABLE REPLACE (R) REPLICATE_DO_DB[u] REPLICATE_DO_TABLE[v] REPLICATE_IGNORE_DB[w] REPLICATE_IGNORE_TABLE[x] REPLICATE_REWRITE_DB[y] REPLICATE_WILD_DO_TABLE[z] REPLICATE_WILD_IGNORE_TABLE[aa] REPLICATION REQUIRE (R) RESET RESIGNAL (R) RESTORE RESTRICT (R) RESUME RETURN (R) RETURNED_SQLSTATE RETURNS REVERSE REVOKE (R) RIGHT (R) RLIKE (R) ROLLBACK ROLLUP ROTATE[ab] ROUTINE ROW ROWS ROW_COUNT ROW_FORMAT RTREE SAVEPOINT SCHEDULE SCHEMA (R) SCHEMAS (R) SCHEMA_NAME SECOND SECOND_MICROSECOND (R) SECURITY SELECT (R) SENSITIVE (R) SEPARATOR (R) SERIAL SERIALIZABLE SERVER SESSION SET (R) SHARE SHOW (R) SHUTDOWN SIGNAL (R) SIGNED SIMPLE SLAVE SLOW SMALLINT (R) SNAPSHOT SOCKET SOME SONAME SOUNDS SOURCE SPATIAL (R) SPECIFIC (R) SQL (R) SQLEXCEPTION (R) SQLSTATE (R) SQLWARNING (R) SQL_AFTER_GTIDS SQL_AFTER_MTS_GAPS SQL_BEFORE_GTIDS SQL_BIG_RESULT (R) SQL_BUFFER_RESULT SQL_CACHE SQL_CALC_FOUND_ROWS (R) SQL_NO_CACHE SQL_SMALL_RESULT (R) SQL_THREAD SQL_TSI_DAY SQL_TSI_HOUR SQL_TSI_MINUTE SQL_TSI_MONTH SQL_TSI_QUARTER SQL_TSI_SECOND SQL_TSI_WEEK SQL_TSI_YEAR SSL (R) STACKED START STARTING (R) STARTS STATS_AUTO_RECALC STATS_PERSISTENT STATS_SAMPLE_PAGES STATUS STOP STORAGE STORED[ac] (R) STRAIGHT_JOIN (R) STRING SUBCLASS_ORIGIN SUBJECT SUBPARTITION SUBPARTITIONS SUPER SUSPEND SWAPS SWITCHES TABLE (R) TABLES TABLESPACE TABLE_CHECKSUM TABLE_NAME TEMPORARY TEMPTABLE TERMINATED (R) TEXT THAN THEN (R) TIME TIMESTAMP TIMESTAMPADD TIMESTAMPDIFF TINYBLOB (R) TINYINT (R) TINYTEXT (R) TO (R) TRAILING (R) TRANSACTION TRIGGER (R) TRIGGERS TRUE (R) TRUNCATE TYPE TYPES UNCOMMITTED UNDEFINED UNDO (R) UNDOFILE UNDO_BUFFER_SIZE UNICODE UNINSTALL UNION (R) UNIQUE (R) UNKNOWN UNLOCK (R) UNSIGNED (R) UNTIL UPDATE (R) UPGRADE USAGE (R) USE (R) USER USER_RESOURCES USE_FRM USING (R) UTC_DATE (R) UTC_TIME (R) UTC_TIMESTAMP (R) VALIDATION[ad] VALUE VALUES (R) VARBINARY (R) VARCHAR (R) VARCHARACTER (R) VARIABLES VARYING (R) VIEW VIRTUAL[ae] (R) WAIT WARNINGS WEEK WEIGHT_STRING WHEN (R) WHERE (R) WHILE (R) WITH (R) WITHOUT[af] WORK WRAPPER WRITE (R) X509 XA XID[ag] XML XOR (R) YEAR YEAR_MONTH (R) ZEROFILL (R)
[a] ACCOUNT: added in 5.7.6 (nonreserved)
[b] ALWAYS: added in 5.7.6 (nonreserved)
[c] CHANNEL: added in 5.7.6 (nonreserved)
[d] COMPRESSION: added in 5.7.8 (nonreserved)
[e] ENCRYPTION: added in 5.7.11 (nonreserved)
[f] FILE_BLOCK_SIZE: added in 5.7.6 (nonreserved)
[g] FILTER: added in 5.7.3 (nonreserved)
[h] FOLLOWS: added in 5.7.2 (nonreserved)
[i] GENERATED: added in 5.7.6 (reserved)
[j] GROUP_REPLICATION: added in 5.7.6 (nonreserved)
[k] INSTANCE: added in 5.7.11 (nonreserved)
[l] JSON: added in 5.7.8 (nonreserved)
[m] MASTER_TLS_VERSION: added in 5.7.10 (nonreserved)
[n] MAX_STATEMENT_TIME: added in 5.7.4 (nonreserved); removed in 5.7.8
[o] NEVER: added in 5.7.4 (nonreserved)
[p] NONBLOCKING: removed in 5.7.6
[q] OLD_PASSWORD: removed in 5.7.5
[r] OPTIMIZER_COSTS: added in 5.7.5 (reserved)
[s] PARSE_GCOL_EXPR: added in 5.7.6 (reserved); became nonreserved in 5.7.8
[t] PRECEDES: added in 5.7.2 (nonreserved)
[u] REPLICATE_DO_DB: added in 5.7.3 (nonreserved)
[v] REPLICATE_DO_TABLE: added in 5.7.3 (nonreserved)
[w] REPLICATE_IGNORE_DB: added in 5.7.3 (nonreserved)
[x] REPLICATE_IGNORE_TABLE: added in 5.7.3 (nonreserved)
[y] REPLICATE_REWRITE_DB: added in 5.7.3 (nonreserved)
[z] REPLICATE_WILD_DO_TABLE: added in 5.7.3 (nonreserved)
[aa] REPLICATE_WILD_IGNORE_TABLE: added in 5.7.3 (nonreserved)
[ab] ROTATE: added in 5.7.11 (nonreserved)
[ac] STORED: added in 5.7.6 (reserved)
[ad] VALIDATION: added in 5.7.5 (nonreserved)
[ae] VIRTUAL: added in 5.7.6 (reserved)
[af] WITHOUT: added in 5.7.5 (nonreserved)
[ag] XID: added in 5.7.5 (nonreserved)
Table 10.3 Keywords and Reserved Words Added in MySQL 5.7 Compared to MySQL 5.6
ACCOUNT ALWAYS CHANNEL COMPRESSION ENCRYPTION FILE_BLOCK_SIZE FILTER FOLLOWS GENERATED (R) GROUP_REPLICATION INSTANCE JSON MASTER_TLS_VERSION NEVER OPTIMIZER_COSTS (R) PARSE_GCOL_EXPR PRECEDES REPLICATE_DO_DB REPLICATE_DO_TABLE REPLICATE_IGNORE_DB REPLICATE_IGNORE_TABLE REPLICATE_REWRITE_DB REPLICATE_WILD_DO_TABLE REPLICATE_WILD_IGNORE_TABLE ROTATE STACKED STORED (R) VALIDATION VIRTUAL (R) WITHOUT XID
Table 10.4 Keywords and Reserved Words Removed in MySQL 5.7 Compared to MySQL 5.6
OLD_PASSWORD
總結
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