/ ** For clarity of the display: All commands are capitalized fixed format
SQL syntax Category: DML, DDL, DCL
(1) DML (Data Manipulation Language, a database manipulation language):
Data: add, modify, delete
(2) DDL (Data Definition Language, a database definition language):
Define the structure of the data table, defined (user data table, model name) of database objects
(3) DCL (Data Control Lanaguage, Data Control Language): Authorization Manager
SQL statement execution order: ①FROM, ②WHERE, ③SELECT
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1.Oracle common commands:
Start Oracle: (1) First check service option "OracleServiceXXX", "OrcaleOraDbllg_home1TNSListener" whether to activate two services;
(2) Open the "Run" or enter cmd into the command line interface, type:
"Sqlplus" or
"Sqlplus username / password"
2. Set the structure of the display:
(1) SET LINESIZE 100; // set per line length
(2) SET PAGESIZE 30; // set of data lines per page number
(3) COL tname FOR A20; // explicitly set the column format
3. User Switching:
CONN [ECT] username / password [AS SYSDBA | SYSUSER] // Switch User
For example: CONN sys / change_on_install AS SYSDBA // change to the superuser
CONN system / manager // switch to common user
4. Basic statement:
SELECT * FROM tab; // query all the tables under the name of the current database
DESC table name; // view the structure of the table
SELECT * FROM table name; // query all the information in the table
. SELECT * FROM user name table name; // specify the user name, look-up tables under the user
SELECT column name [alias], column name [alias] .... FROM table name; // query information specified column
SELECT column name AS alias FROM table; // Define the table name, Oracle statement AS can be omitted
SELECT job, sal * 10 + 20 * 10 as income FROM emp; // query career, 10 times the monthly salary multiplied by 10 plus 20
The SELECT the DISTINCT column names FROM table; // remove duplicate query sequence information and the information therein, the DISTINCT deduplication
SELECT 'constant', column names FROM table; // query constant, constant need to use the ' ' '( single quotes ), including up
SELECT 'constant' || column names FROM table; // use " || " connection for data display
HOST copy d: \ hello \ a.txt d: copy hello \ b.txt // perform file \
5. Query defined
Defining a query, execute basic statement:
③SELECT [DISTINCT] column name [alias]
①FROM table name [alias]
②WHERE qualification;
Analyzing common (performance operators is greater than a plurality of operators):
• relational operators:>, <,> =,> =, =, =;!
• Logical operators: AND, OR, NOT [Non];
• special operators: BETWEEN ... AND, IN, NOT IN, LIKE,
• " % ": match 0, 1 or any number of characters
• " _ ": matches any one character
SELECT * FROM table name the NOT the WHERE ( Age> 10 SAL OR <100 000 ) ; // table query younger than 10 or higher wages 100,000 personnel information, attention parentheses
SELECT * FROM table ename the LIKE the WHERE 'A % '; // query all names beginning with A
SELECT * FROM table ename the LIKE the WHERE ' _ A % '; // query for all second name beginning with A
SELECT * FROM table ename the LIKE the WHERE ' % A % '; // query all arbitrary bit A Name
6. Sort query:
SQL statement execution order
③SELECT [DISTINCT] column name [alias]
①FROM table name [alias]
②WHERE qualification;
④ [ORDER BY sort field names [ASC | DESC]]
BY the ORDER : The Sort Field
The ASC : ascending order, if the type of sorting is not set, using the default ascending
DESC : descending order, shall be manually set
* The FROM emp the SELECT the ORDER BY SAL DESC ; // query in descending order according to salary
* The FROM emp the SELECT the WHERE Age = 11 the ORDER BY SAL DESC ; // Query the age of 11 pay according to descending order
* The FROM emp the SELECT the WHERE Age = 11 the ORDER BY SAL DESC , the HireDate ASC ; // Query the age of 11 pay according to descending order, the entry date in ascending order