EXPLAIN SELECT select_statement
by Tony Butcher
Sams Teach Yourself MySQL in 21 Days, Second Edition
- 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
EXPLAIN SELECT select_statement
Description: Provides the query plan for a SELECT. MySQL shows how it will join any tables and in which order.
This can enable you to see whether the query optimizer will join the tables in the optimal order. You can override this order using a SELECT with a STRAIGHT_JOIN clause.
Description in: Day 18
See also: SELECT and the STRAIGHT_JOIN clause
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