11 Linux ulanyjylary üçin MySQL maglumat bazasy Söhbetdeşlik soraglary we jogaplary
Tecmint jemgyýeti tarapyndan gowy baha berlen iki sany MySQL makalasyny eýýäm çap etdik. Bu, MySQL Söhbetdeşlik seriýasyndaky üçünji makala we Söhbetdeşlik reanry sütünindäki on alty makala.
- 15 esasy MySQL söhbetdeşlik soraglary
- Araçylar üçin 10 MySQL maglumat bazasynyň söhbetdeşlik soraglary
Siziň goldawyňyz sebäpli bu ýere ýetdik we geljekde siziň ahyrzamanyňyzy gözleýäris. Bu ýerde bu makalada Söhbetdeşlik aspektine degişli sorag MySQL-iň amaly tarapyna jemleneris.
Jogap: Aşakdaky MySQL buýrugy serwer wersiýasyny we häzirki saýlanan Maglumat bazasyny görkezer.
mysql> SELECT VERSION(), DATABASE(); +-------------------------+------------+ | VERSION() | DATABASE() | +-------------------------+------------+ | 5.5.34-0ubuntu0.13.10.1 | NULL | +-------------------------+------------+ 1 row in set (0.06 sec)
Maglumat bazasynyň sütüninde NULL bahasy görkezilýär, sebäbi hiç hili maglumat bazasyny saýlamadyk. Şeýlelik bilen, aşakdaky buýrukda görkezilişi ýaly maglumat bazasyny saýlaň.
mysql> use Tecmint; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed
mysql> select VERSION(), DATABASE(); +-------------------------+------------+ | VERSION() | DATABASE() | +-------------------------+------------+ | 5.5.34-0ubuntu0.13.10.1 | tecmint | +-------------------------+------------+ 1 row in set (0.00 sec)
Jogap: Aşakdaky jümle, ulanyjynyň dan başga ' Tecmint ' tablisasyndaky ähli ulanyjylaryň sütünlerini görkezer. SAM '.
mysql> SELECT * FROM Tecmint WHERE user !=SAM; +---------------------+---------+---------+---------+---------+-------+ | date | user | host | root | local | size | +---------------------+---------+---------+---------+---------+-------+ | 2001-05-14 14:42:21 | Anthony | venus | barb | venus | 98151 | | 2001-05-15 08:50:57 | TIM | venus | phil | venus | 978 | +---------------------+---------+---------+---------+---------+-------+
Ans: AND operatory (=) ulananymyzda, ýa-da operator (! =) ulananymyzda ulanylýar. AND Operator bilen (=) mysal.
mysql> SELECT * FROM mail WHERE user = SAM AND root = phil
ORA-da Operator bilen (! =) Mysal.
mysql> SELECT * FROM mail WHERE user != SAM OR root != phil +---------------------+---------+---------+---------+---------+-------+ | date | user | host | root | local | size | +---------------------+---------+---------+---------+---------+-------+ | 2001-05-14 14:42:21 | Anthony | venus | barb | venus | 98151 | +---------------------+---------+---------+---------+---------+-------+
- =: deňdir diýmekdir
- !=: bilen deň däl
- ! : NOT Operator däl
AND & OR MySQL-da operatorlara goşulmak hökmünde seredilýär.
Jogap: MySQL-daky talap IFNULL() jümlesini ulanyp ýazylyp bilner. IFNULL() jümlesi ilkinji argumentini synap görýär we NULL bolmasa ýa-da ikinji argumentini yzyna gaýtaryp berýär.
mysql> SELECT name, IFNULL(id,'Unknown') AS 'id' FROM taxpayer; +---------+---------+ | name | id | +---------+---------+ | bernina | 198-48 | | bertha | Unknown | | ben | Unknown | | bill | 475-83 | +---------+---------+
Jogap: aboveokarda görkezilen ssenariýa ýetmek üçin ORDER BY bilen bilelikde LIMIT maddasyny ulanmalydyrys.
mysql> SELECT * FROM name LIMIT 1; +----+------+------------+-------+----------------------+------+ | id | name | birth | color | foods | cats | +----+------+------------+-------+----------------------+------+ | 1 | Fred | 1970-04-13 | black | lutefisk,fadge,pizza | 0 | +----+------+------------+-------+----------------------+------+
mysql> SELECT * FROM profile LIMIT 5; +----+------+------------+-------+-----------------------+------+ | id | name | birth | color | foods | cats | +----+------+------------+-------+-----------------------+------+ | 1 | Fred | 1970-04-13 | black | lutefisk,fadge,pizza | 0 | | 2 | Mort | 1969-09-30 | white | burrito,curry,eggroll | 3 | | 3 | Brit | 1957-12-01 | red | burrito,curry,pizza | 1 | | 4 | Carl | 1973-11-02 | red | eggroll,pizza | 4 | | 5 | Sean | 1963-07-04 | blue | burrito,curry | 5 | +----+------+------------+-------+-----------------------+------+
mysql> SELECT * FROM profile ORDER BY birth LIMIT 1; +----+------+------------+-------+----------------+------+ | id | name | birth | color | foods | cats | +----+------+------------+-------+----------------+------+ | 9 | Dick | 1952-08-20 | green | lutefisk,fadge | 0 | +----+------+------------+-------+----------------+------+
Jogap: Ikisiniň hem artykmaçlyklary we kemçilikleri bar. Wagtyň geçmegi bilen MySQL-i has gowy görýärin.
- Mysql FOSS.
- MySQL göçme.
- MYSQL hem GUI, hem buýruk buýrugy goldaýar.
- MySQL administrasiýasy Talap brauzerinde goldanýar.
Jogap: MySQL-da häzirki senäni almak aşakdaky SELECT beýannamasyny ýerine ýetirmek ýaly ýönekeý.
mysql> SELECT CURRENT_DATE(); +----------------+ | CURRENT_DATE() | +----------------+ | 2014-06-17 | +----------------+
Jogap: MySQL tablisasyny ýa-da tutuş maglumat bazasyny XML faýlyna eksport etmek üçin -e (eksport) opsiýasyny ulanýarys. Uly tablisalar bilen el bilen amala aşyrmaly bolmagymyz mümkin, ýöne kiçi tablisalar üçin phpMyAdmin ýaly programmalar bu işi edip biler.
MySQL-iň ýerli buýrugy muny edip biler.
mysql -u USER_NAME –xml -e 'SELECT * FROM table_name' > table_name.xml
USER_NAME maglumatlar bazasynyň ulanyjy ady bolan ýerinde, table_name XML-e eksport edýän tablisamyz we table_name.xml maglumatlaryň saklanýan xml faýlydyr.
Jogap: MySQL_pconnect() MySQL maglumatlar bazasyna dowamly bir baglanyşyk açýar, bu sahypa her gezek sahypa ýüklenende maglumatlar bazasynyň açylmaýandygyny aňladýar we şonuň üçin biz Dowamly baglanyşygy ýapmak üçin MySQL_close() ulanyp bilemok.
MySQL_pconnect bilen MySQL_connect arasynda gysga tapawut.
MySQL_pconnect-den tapawutlylykda, MySQL_connect - MySQL_close() jümlesini ulanyp islendik wagt ýapylyp bilinjek sahypa ýüklenende maglumatlar bazasyny açýar.
Jogap: Aşakdaky buýruk ulanyjy tablisasynyň ähli görkezijilerini görkezer.
mysql> show index from user; +-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | +-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | user | 0 | PRIMARY | 1 | Host | A | NULL | NULL | NULL | | BTREE | | | | user | 0 | PRIMARY | 2 | User | A | 4 | NULL | NULL | | BTREE | | | +-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ 2 rows in set (0.00 sec)
Jogap: CSV vergul bilen bölünen bahalar, nyşanlaryň aýry-aýry bahalary. CSV tablisasy maglumatlary ýönekeý tekstde we tablisa görnüşinde saklaýar. Adatça her setirde bir ýazgy bar.
Her ýazgy belli bir bölüjiler bilen bölünýär (verma, ýarym içege,…), bu ýerde her ýazgynyň birmeňzeş meýdany bar. CSV tablisalary import etmek we eksport etmek üçin telefon aragatnaşyklaryny saklamak üçin iň giňden ulanylýar we islendik tekst maglumatlary saklamak üçin ulanylýar.
Bularyň hemmesi häzirlikçe. Men ýene-de bir gyzykly makala bilen gelerin, adamlar okamagy halarsyňyz. Soňra “Tecmint” -e birikdiriň we aşakdaky teswirler bölüminde bize gymmatly pikirleriňizi bermegi ýatdan çykarmaň.