Existen unas serie de palabras que estan reservadas en SQL y en los motores de base de datos, es decir no las podemos utilizar o para utilizarlas tenemos que buscar una forma especial de tratarlas. Por ejemplo no podemos elegir group como nombre de una tabla.

Listado de palabras reservadas en MySQL:

ACCESSIBLE, 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, EXISTS, EXIT, EXPLAIN, FALSE, FETCH, FLOAT, FLOAT4, FLOAT8, FOR, FORCE, FOREIGN, FROM, FULLTEXT, 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, IO_AFTER_GTIDS, IO_BEFORE_GTIDS, 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, NONBLOCKING, NOT, NO_WRITE_TO_BINLOG, NULL, NUMERIC, ON, OPTIMIZE, OPTION, OPTIONALLY, OR, ORDER, OUT, OUTER, OUTFILE, PARTITION, PRECISION, PRIMARY, PROCEDURE, PURGE, RANGE, READ, READS, READ_WRITE, REAL, REFERENCES, REGEXP, RELEASE, RENAME, REPEAT, REPLACE, REQUIRE, RESIGNAL, RESTRICT, RETURN, REVOKE, RIGHT, RLIKE, 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, STRAIGHT_JOIN, 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, WHEN, WHERE, WHILE, WITH, WRITE, XOR, YEAR_MONTH, ZEROFILL.
http://dev.mysql.com/doc/refman/5.7/en/reserved-words.html