11 Ibi-ipamọ data MySQL Niwaju "Awọn ibeere Ifọrọwanilẹnuwo ati Awọn Idahun" fun Awọn olumulo Lainos
A ti ṣe atẹjade awọn nkan MySQL meji, ti o ni itẹlọrun nipasẹ Tecmint Community. Eyi ni nkan kẹta lori jara Ifọrọwanilẹnuwo MySQL ati mẹrindinlogun ninu Iwe-ẹri Ifọrọwanilẹnuwo Iwe-ẹri.
- 15 Ipilẹ Awọn ibeere Ifọrọwanilẹnuwo MySQL
- Awọn ibeere Ifọrọwanilẹnuro data data MySQL 10 fun Awọn agbedemeji
A ti de nibi gbogbo nitori ti atilẹyin tirẹ ati pe a wa kanna ni ọjọ iwaju fọọmu opin rẹ. Nibi ni nkan yii a yoo ni idojukọ lori abala iṣe ti MySQL, ibeere ti o yẹ fun abala Ifọrọwanilẹnuwo.
Idahun: Isalẹ aṣẹ MySQL yoo fi ikede olupin han ati Lọwọlọwọ ti o yan Ibi ipamọ data.
mysql> SELECT VERSION(), DATABASE(); +-------------------------+------------+ | VERSION() | DATABASE() | +-------------------------+------------+ | 5.5.34-0ubuntu0.13.10.1 | NULL | +-------------------------+------------+ 1 row in set (0.06 sec)
Ninu Iwe Iwe data o n fihan NULL iye nitori a ko yan eyikeyi ibi ipamọ data. Nitorinaa, yan ibi data bi o ṣe han ninu aṣẹ atẹle.
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)
Ans: Alaye ti o wa ni isalẹ yoo fihan gbogbo awọn ọwọn gbogbo awọn olumulo lati ori tabili ' Tecmint ' ayafi olumulo ' 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 | +---------------------+---------+---------+---------+---------+-------+
> Apẹẹrẹ ti (=) pẹlu ATI Oniṣẹ.
mysql> SELECT * FROM mail WHERE user = SAM AND root = phil
Apẹẹrẹ ti (! =) Pẹlu TABI Oṣiṣẹ.
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 | +---------------------+---------+---------+---------+---------+-------+
- =: tumọ si Dogba si
- ! = : Ko dọgba si
- ! : ṣe aṣoju ṢEṢẸ oniṣẹ
Awọn ATI & TABI ti ṣe itọju bi didapọ awọn oniṣẹ ni MySQL.
Ans: Ibeere ninu MySQL ni a le kọ ni deede nipa lilo alaye IFNULL() . Ọrọ IFNULL() ṣe idanwo ariyanjiyan akọkọ rẹ ati pada ti ko ba jẹ NULL, tabi pada ariyanjiyan keji rẹ, bibẹkọ.
mysql> SELECT name, IFNULL(id,'Unknown') AS 'id' FROM taxpayer; +---------+---------+ | name | id | +---------+---------+ | bernina | 198-48 | | bertha | Unknown | | ben | Unknown | | bill | 475-83 | +---------+---------+
Ans: A nilo lati lo LIMIT ipinfunni pẹlu PẸLU NIPA lati ṣaṣeyọri iṣẹlẹ ti a ṣalaye loke.
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 | +----+------+------------+-------+----------------+------+
Ans: Daradara mejeeji ni awọn anfani ati ailagbara rẹ. Bi ọrọ ti akoko Mo fẹ MySQL.
- Mysql ni FOSS.
- MySQL jẹ amudani.
- MYSQL n ṣe atilẹyin GUI mejeeji bakanna bi Tọṣẹ Tọ.
- Isakoso MySQL ni atilẹyin lori Ẹrọ aṣawakiri Ibeere.
Idahun: Gbigba ọjọ lọwọlọwọ ninu MySQL jẹ rọrun bi ṣiṣe Gbólóhùn Yiyan Yan ni isalẹ.
mysql> SELECT CURRENT_DATE(); +----------------+ | CURRENT_DATE() | +----------------+ | 2014-06-17 | +----------------+
Ans: A lo aṣayan ‘-e‘ (okeere) lati gbe tabili MySQL jade tabi gbogbo ibi ipamọ data sinu faili XML kan. Pẹlu awọn tabili nla a le nilo lati ṣe pẹlu ọwọ ṣugbọn fun awọn tabili kekere, awọn ohun elo bii phpMyAdmin le ṣe iṣẹ naa.
Aṣẹ abinibi ti MySQL le ṣe.
mysql -u USER_NAME –xml -e 'SELECT * FROM table_name' > table_name.xml
Nibiti USER_NAME ti jẹ orukọ olumulo ti Database, orukọ tabili ni tabili ti a n gbe okeere si XML ati table_name.xml ni faili xml nibi ti o ti fipamọ data.
t ko le lo MySQL_close() lati pa asopọ ti o tẹsiwaju.
Iyatọ kukuru laarin MySQL_pconnect ati MySQL_connect ni.
Ko dabi MySQL_pconnect, MySQL_connect - Ṣii aaye data ni gbogbo igba ti oju-iwe ti kojọpọ eyiti o le wa ni pipade nigbakugba nipa lilo alaye MySQL_close().
Ans: Ofin atẹle yoo fihan gbogbo awọn atọka ti tabili ‘olumulo’.
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)
Awọn idahun: CSV duro fun Awọn iye-Apa-Apata Aka Awọn iye-kikọ-Awọn Iyapa. Tabili CSV tọju data ni ọrọ pẹtẹlẹ ati ọna kika tabili. Nigbagbogbo o ni igbasilẹ kan fun laini kan.
Igbasilẹ kọọkan ti ya nipasẹ awọn oniduuro kan pato (Comma, Ologbele-oluṣafihan,…) nibiti igbasilẹ kọọkan ni ọkọọkan ọkọọkan. Awọn tabili CSV ni lilo pupọ julọ lati tọju awọn olubasọrọ foonu si Wọle ati Gbe wọle ati pe a le lo lati tọju eyikeyi iru alaye ọrọ lasan.
Iyẹn ni gbogbo fun bayi. Emi yoo wa nibi lẹẹkansi pẹlu nkan Nkan miiran ti Nkan, iwọ eniyan yoo nifẹ lati ka. Titi lẹhinna wa ni aifwy ati sopọ si Tecmint ati Maṣe gbagbe lati pese wa pẹlu awọn esi rẹ ti o niyelori ni abala ọrọ asọye ni isalẹ.