- Copyright
- About the Author
- Acknowledgments
- We Want to Hear from You!
- Introduction
- At a Glance
- At a Glance
- Querying Data
- Joins and Indexes
- Operators and Functions in MySQL
- Using PHP
- Using the Perl DBI
- Using the C API
- C and MySQL
- When to Use C, and When Not To
- Datatypes
- Compiling and Linking
- Connecting to Your Database
- Disconnecting from a Database
- Handling Errors
- A Simple Connection Script
- Running Queries That Return a Resultset
- A Simple Query Program
- Handling Resultsets
- Queries That Return No Resultset
- Summary
- Q&A
- Workshop
- Security
- At a Glance
- Appendices
- Data Type Reference
- SQL Reference
- ALTER [IGNORE] TABLE table_name action_list
- ANALYZE TABLE table_name[,table_name...]
- BACKUP TABLE table_name[,table_name...] TO '/backup/directory'
- BEGIN
- CHECK TABLE table_name[,table_name,...] [options]
- COMMIT
- CREATE DATABASE [IF NOT EXISTS] database_name
- CREATE [AGGREGATE] FUNCTION function_nameRETURNS {STRING|REAL|INTEGER} SONAME shared_library_name
- CREATE [UNIQUE|FULLTEXT] INDEX index_nameON table_name (column_list)
- CREATE [TEMPORARY] TABLE[IF NOT EXISTS] table_name[(create_definition,...)][table_options] [select_statement]
- CROSS JOIN
- DELETE
- DESCRIBE table_name [column_name]
- DESC
- DROP DATABASE [IF EXISTS] database_name
- DROP FUNCTION function_name
- DROP INDEX index_name ON table_name
- DROP TABLE [IF EXISTS] table_name[,table_name...]
- EXPLAIN SELECT select_statement
- EXPLAIN table_name
- FLUSH flush_option[,flush_option...]
- GRANT
- HANDLER
- INNER JOIN
- INSERT
- KILL thread_id
- LEFT JOIN
- LEFT OUTER JOIN
- LOAD DATA INFILE
- LOCK TABLES
- NATURAL JOIN
- NATURAL LEFT JOIN
- NATURAL LEFT OUTER JOIN
- NATURAL RIGHT JOIN
- NATURAL RIGHT OUTER JOIN
- OPTIMIZE TABLE table_name[,table_name...]
- RENAME TABLE table_name TO new_table_name[, table_name2 TO new_table_name2 ...]
- REPAIR TABLE table_name[,table_name,...] [options]
- REPLACE
- RESTORE TABLE table_name[,table_name...] FROM '/backup/directory'
- REVOKE privileges [(column_list)][,privileges [(column_list)]...]ON {database_name.table_name}FROM username@hostname
- RIGHT JOIN
- RIGHT OUTER JOIN
- ROLLBACK
- SELECT
- SET [OPTION] option=value,...
- SHOW keyword parameters
- TRUNCATE TABLE table_name
- UNION
- UNLOCK TABLES
- UPDATE
- USE database_name
- Function and Operator Reference
- &, Bitwise AND
- &&, Logical AND
- |, Bitwise OR
- ||, Logical OR
- x<<n, Bitwise Left-Shift
- x>>n, Bitwise Right-Shift
- ~, Bitwise Inversion
- !, Not
- +, Addition
- -, Subtraction
- *, Multiplication
- /, Division
- %, Modulo
- -, Unary Minus
- =, Equals
- <=>, NULL-Safe Equals
- <>, Not Equal To
- >, Greater Than
- >=, Greater Than or Equal To
- <, Less Than
- <=, Less Than or Equal To
- ABS(x)
- ACOS(x)
- ADDDATE(date,INTERVAL expression type)
- AES_DECRYPT(string,key)
- AES_ENCRYPT(encrypted_string,key)
- AND, Logical
- ASCII(string)
- ASIN(x)
- ATAN(x)
- ATAN(x,y)
- ATAN2(x,y)
- AVG(expression)
- BENCHMARK(count,expression)
- expression BETWEEN min AND max
- BIN(n)
- BINARY
- BIT_AND(expression)
- BIT_COUNT(expression)
- BIT_OR(expression)
- CASE
- CEILING(x)
- CHAR(n1[,n2...])
- CHAR_LENGTH(string)
- CHARACTER_LENGTH(string)
- COALESCE(value[,...])
- CONCAT(string1[,string2,...])
- CONCAT_WS(separator,string1[,string2,...])
- CONNECTION_ID()
- CONV(n,base1,base2)
- COS(x)
- COT(x)
- COUNT(expression)
- COUNT(DISTINCT expression[,expression...])
- CURDATE()
- CURRENT_DATE
- CURRENT_TIME
- CURRENT_TIMESTAMP
- CURTIME()
- DATABASE()
- DATE_ADD(date,INTERVAL expression type)
- DATE_FORMAT(date,format)
- DATE_SUB(date,INTERVAL expression type)
- DAYNAME()
- DAYOFMONTH(date)
- DAYOFWEEK(date)
- DAYOFYEAR()
- DECODE(encoded_string,password)
- DEGREES(x)
- DES_DECRYPT(encrypted_string [, key_string])
- DES_ENCRYPT(string [, (key_number | key_string)])
- ELT(n,string1[,string2,string3...])
- ENCODE(string,password)
- ENCRYPT(string[,salt])
- EXP(x)
- EXPORT_SET(bits,on_str,off_str[,separator][,num_bits])
- EXTRACT(type FROM date)
- FIELD(string,string1[,string2,string3...])
- FIND_IN_SET(string,string_set)
- FLOOR(x)
- FORMAT(x,d)
- FROM_DAYS(num)
- FROM_UNIXTIME(unix_timestamp[,format])
- GET_LOCK(string,timeout)
- GREATEST(x1,x2[,...])
- HEX(n)
- HOUR(time)
- IF(test_expression,expression_true,expression_false)
- IFNULL(expression1,expression2)
- expression IN (value[,...])
- INET_ATON(expression)
- INET_NTOA(expression)
- INSERT(string,position,length,substr)
- INSTR(string,substr)
- INTERVAL(x,n0,n1[,n2,...])
- expression IS NOT NULL
- expression IS NULL
- ISNULL(expression)
- LAST_INSERT_ID([expression])
- LCASE(string)
- LEAST(x1,x2[,...])
- LEFT(string,length)
- LENGTH(string)
- string LIKE pattern [ESCAPE escape_character]
- LOAD_FILE(filename)
- LOCATE(substr,string[,position])
- LOG()
- LOG10(x)
- LOWER()
- LTRIM(string)
- MAKE_SET(bits,string1[,string2...])
- MASTER_POS_WAIT(log_name,log_pos)
- MATCH (column1[,column2,...] AGAINST (string)
- MAX(expression)
- MD5(string)
- MID(string,position,length)
- MIN(expression)
- MINUTE(time)
- MOD(n,m)
- MONTH()
- MONTHNAME()
- NOT IN
- string NOT LIKE pattern [ESCAPE escape_character]
- string NOT REGEXP pattern
- string NOT RLIKE pattern
- NOT
- NOW()
- NULLIF(expression1,expression2)
- OCT(n)
- OCTET_LENGTH(string)
- OR
- ORD()
- PASSWORD(string)
- PERIOD_ADD(period,months)
- PERIOD_DIFF(period1,period2)
- PI()
- POSITION(substr IN string)
- POW()
- POWER(x,y)
- QUARTER()
- RADIANS(x)
- RAND([n])
- string REGEXP pattern
- RELEASE_LOCK(string)
- REPEAT(string,count)
- REPLACE(string,from_string,to_string)
- REVERSE(string)
- RIGHT(string,length)
- string RLIKE pattern
- ROUND(x)
- ROUND(x,d)
- RPAD()
- RTRIM()
- SEC_TO_TIME(seconds)
- SECOND()
- SESSION_USER()
- SHA(string)
- SIGN(x)
- SIN()
- SOUNDEX(string)
- SPACE(length)
- SQRT(x)
- STD(expression)
- STDDEV()
- STRCMP(string1,string2)
- SUBDATE(date,INTERVAL expression type)
- SUBSTRING(string,delimiter,count)
- SUBSTRING_INDEX(string,delimiter,count)
- SUM(expression)
- SYSDATE()
- SYSTEM_USER()
- TAN()
- TIME_FORMAT(time)
- TIME_TO_SEC(time)
- TO_DAYS(date)
- TRIM([[LEADING|TRAILING|BOTH] [substring] FROM] string)
- TRUNCATE(x,d)
- UCASE(string)
- UNIX_TIMESTAMP([date])
- UPPER(string)
- USER()
- VERSION()
- WEEK(date[,first])
- WEEKDAY(date)
- YEAR(date)
- YEARWEEK(date[,first])
- The PHP API
- mysql_affected_rows([link_identifier])
- mysql_close([link_identifier])
- mysql_connect([server[,username[,password[,new_link]]]])
- mysql_create_db(database_name[,link_identifier])
- mysql_data_seek(result,row_number)
- mysql_db_name(result,offset[,field])
- mysql_db_query(database_name,query[,link_identifier][,result mode])
- mysql_drop_db(database_name[,link_identifier])
- mysql_errno([link_identifier])
- mysql_error([link_identifier])
- mysql_escape_string(raw_string)
- mysql_fetch_array(result)
- mysql_fetch_assoc(result)
- mysql_fetch_field(result,[offset])
- mysql_fetch_lengths(result)
- mysql_fetch_object(result)
- mysql_fetch_row(result)
- mysql_field_flags(result,offset)
- mysql_field_len(result,offset)
- mysql_field_name(result,offset)
- mysql_field_seek(result,offset)
- mysql_field_table(result,offset)
- mysql_field_type(result,offset)
- mysql_free_result(result)
- mysql_get_client_info()
- mysql_get_host_info([link_identifier])
- mysql_get_proto_info([link_identifier])
- mysql_get_server_info([link_identifier])
- mysql_insert_id([link_identifier])
- mysql_list_dbs([link_identifier])
- mysql_list_fields(database_name,table_name[,link_identifier])
- mysql_list_tables(database_name,[,link_identifier])
- mysql_num_fields(result)
- mysql_num_rows(result)
- mysql_pconnect([server[,username[,password]]])
- mysql_query(query[,link_identifier][,result_mode])
- mysql_real_escape_string(raw_string[,link_identifier])
- mysql_result(result,row_offset[,field])
- mysql_select_db(database_name[,link_identifier])
- mysql_tablename(result,offset)
- mysql_unbuffered_query(query[,link_identifier][,result_mode])
- Index
PERIOD_DIFF(period1,period2)
Description: Returns the number of months between period1 and period2 (both in the format YYYYMM or YYMM). The result will be positive if period1 is later than period2.
Examples:
PERIOD_DIFF(200212,200301) returns -1.
PERIOD_DIFF(0302,0212) returns 2.
See also: PERIOD_ADD()
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