Oracle

View Session:SELECT * FROM v$session where username are not nullSelect Username,count (username) from v$session where username isn't null GROUP by usernameCurrent number of connections:Select COUNT (*) from v$processView settings for the number of

The database type is the actual value of date type such as: 2017/7/11 14:24:19Solution IdeasForeground UI time to the day after tomorrow is string not converted directly to receive time string in MyBatisForeground UI code easy UI Time

--Create a data fileCreateTablespace--Create a table space and create a data file at the same timeCreate TemporaryTablespace--Create a temporary data file while creating a temporary table spaceAlterTablespace ...AddDataFile--to add a data file to a

Oracle database-Common operations directivesView port number DirectivesNetstat–aClear screen:Sql> Clear Scre; SQL> Host CLS;Table SpaceCREATE TABLE Spacesql> Create tablespace tc20 datafile 'e:\tc20_data_dbf' size 20m autoextend on Next 5m maxsize

To view the table structure:See field names and data typesSELECT * FROM cols WHERE table_name=upper (' table_name ')To view the primary key:SELECT * from user_constraints where constraint_type= ' P 'and Table_name=upper (' table_name ')Other than

--function1.oracle self-to_date,to_number standard function2. Custom Functions--Custom Function syntax1 CREATE OR REPLACE FUNCTIONfunction_name2 [(PARAMETERS [MODEL]datatype ...) ]3 RETURNDataType is| as4 [local_variable_declarations, .....]5 BEGIN6

Statement:TableName Oldcname Newcname; --Modify field namestableNameModify (cloumnname data type ); --Modifying data typesFor example:1. Create a table:CREATE TABLE Student (ID VARCHAR2 (+) primary key,NameVARCHAR2 (8) NOT NULL,Age Number);2. Modify

1. Create a normal user tableCreate Table Demo ( intnotnull, varchar(ten), varchar (default'123' ,primary Key (ID))2. Create a sequence sequenceCreate sequence Seq_demo by 1-Self-increment 1 with 1--Start value 1 Nomaxvalue--No

A one-to-many relationship in development is often used, and yesterday a customer problem was asked to organize the information for all feedback tasks into a single line to show and export Excel.My database correspondence: The feedback task task

Selectp.id,p.order_num,p.image_url,p.url,p.image_topic, P.is_download, P.big_image_url, P.begin _time,p.end_time fromPage_index_img PwhereP.is_delete='N' andP.image_type=7 andP.url=app andNow

Oracle Paging query statements make one of our most commonly used statements, as described below, for the use of Oracle paging query statements, and if you are interested in this aspect, you may wish to take a look.Oracle Paging query statements can

1. Benefits of Automatic data file expansion1) does not appear because there is no remaining space available to the data cannot be written2) Minimize man-made maintenance3) can be used in databases where important levels are not very large, such as

The use of the--oracle trunc () function/************** Date ********************/1.select trunc (sysdate) from dual--2013-01-06 today's date is 2013-01-062.select trunc (sysdate, ' mm ') from dual--2013-01-01 returns the first day of the

windows+r→ type Sqlplus, enter the installed Oracle Database Super Administrator account password to log in. Show:Success.To create a table space:To create a user and default tablespace:Authorize the user to create a database operation:Code:sql>

First, before we talk about Plsql develope connect to Oracle database configuration, let's talk about what to do if you don't have to plsql develope to connect to the Oracle database, which is to install the Oracle database natively, but this is a

1. View All Users:SELECT * from Dba_users;SELECT * from All_users;SELECT * from User_users;2. View user or role system permissions (System permissions that are directly assigned to a user or role):SELECT * from Dba_sys_privs; SELECT * from

Management of Oracle Tables--Adding dataInserting data into a table using the INSERT statementInsert Data basic syntax:INSERT into table[(column [, Column ...])] VALUES (value [, value ...]);insert into table name [(column name [, column Name 2 ...])

Summary of merge into usage in Oracle (Source: http://www.cnblogs.com/dongsheng/p/4384754.html)causes :Some time ago, because it involves a table of big data operations, to make additions and deletions at the same time, I and master think a lot of

Recently participated in a number of interviews, summed up the competition in the Oracle development post most frequently asked what questions:1, delete and truncate difference? 1) Truncate is a DDL statement. Delete is a DML statement;2) Truncate

Recently participated in several interviews. Summarize the most frequently asked questions about the competition for Oracle development positions:1, delete and truncate difference? 1) Truncate is a DDL statement, and delete is a DML statement;2)