Oracle

Structure operations on a tableAdd increaseALTER TABLE name drop (column character type (length));Modify ChangeDESC Dept; Look up the table structureOperations on recordsSelect Column name from table name where condition checkUpdate student Set

Transaction:A transaction is a set of related actions performed as a single logical unit of work.These operations require all or none of them to be completed.Reasons for using transactions: Ensure data is safe and effective.Four characteristics of a

I. VARCHAR2 (10) and number should be converted why type?When Oracle turns into MySQL:VARCHAR2 (10) can be turned into varchar (10)Number depends on what type of data is stored in Oracle:1, if the integer type, then MySQL, with an int can be;2, if

1 CREATE OR REPLACE TriggerTrig_solr_index_el_lesson2AfterUpdate ofLessonid, Lessonname, lessongoal, note, TeacherName, Teacherid, Classidname, ClassID, Crtime, statusOr Delete or Insert onEl_lesson3 forEach Row4 Declare5 --Local Variables

Note the point:1: A sequence can be shared by multiple tables.2: The number sequence generated by sequence shared by multiple tables is always continuous and does not start again.3: If the sequence is no longer used, delete it.SELECT * from DAYSBFJ.

Oracle Statement Optimization 1Optimization is choosing the most efficient way to execute SQL statements. The Oracle Optimizer chooses what it deems most effectivemethod to execute the SQL statement.1. Is null and is not NULLIf a column has a null

SELECT a.table_name table name,c.comments Table notes,A.column_name Field Name,REPLACE (DECODE (A.data_type,' DATE ',' DATE ',' VARCHAR2 ',' VARCHAR2 (' | | A.data_length | | ‘)‘,' Number ',' Number (' | | a.data_precision | | ', ' | | A.data_scale |

1. PL/SQL Interpretation Plan windowAdvantages: AspectsCons: See limited information2. Explain_plan forEasier to optimize for a sentence3, SqlplusEnter the command in Sqlplus:Set Autotrace onSELECT * from EMP;After the data is displayed, follow the

Original Address--http://blog.csdn.net/qq525099302/article/details/47253641SELECT * FROM b_role_authority as of timestamp to_timestamp(‘2015-07-25‘,‘yyyy-mm-dd‘)Note: The table structure changes after the invalid, can only query for a period of time

INSTR Usage:INSTR (string,substring,position,ocurrence)Explanation: string: source stringSubString: substring to findPosition: The start position of the lookup. If the starting position is 0, the return value is 0, and when the starting position is

When your application has called the stored procedure, and the node has dozens of or hundreds, the wrong is not a very troublesome thing, this time, I suggest to write to the database, below is a demo I do.1. Create an error log record tabledrop

Disclaimer: This article is for bloggers in the project to use some of the common commands, do not reprint.Oracle Common Naming SummaryTo create a table space:--create tablespace VMS--datafile ' e:\vms.dbf '--size 32000M--extent Management local

Bitand () function in Oraclereturns the result of two numeric numeric values after a bitwise AND operation.GrammarBitand (NExpression1, NExpression2)ParametersNExpression1, NExpression2Specifies the two numeric values for the bitwise AND operation.

Oracle Database batch processing files and oracle Database Batch Processing Directory structure Initialization Script |----orcl_sql|----init_user.sql|----tab_home.sql |----TAB_USER.sql |----init.bat Init. bat @ Echo off @ echo success @

Oracle hierarchical query and Oracle hierarchical Query The syntax for Oracle hierarchical query is as follows: The following are based on two questions: 1. according to the chronological order, the English names of the twelve constellations are

Sort common e functions, oracle Functions Recently I learned about Oracle databases and often encountered Oracle database functions. After careful consideration, I summarized some common Oracle database functions.   ----------------------------------

Vertical table and horizontal table, vertical table horizontal table Vertical vs horizontal The following example shows the traditional horizontal table structure: 　　Table HR 　 　　ID 　　Surname 　　Name 　　Department 　　Gender

Mysql, SQL server, oracle Database paging query and Analysis (Operation Manual), mysqloracle 1. mysql paging Query Method 1: select * from table order by id limit m, n;   This statement means to query m + n records, remove the first m records, and

Oracle Display object space usage show_space Tom wrote a script to view the object space usage of the Oracle database.The following shows how to use it: -Tool source code CREATE OR REPLACE PROCEDURE show_space(p_segname IN VARCHAR2,

Oraclebetweenand Boundary Problems -- Create a table create table test_hsj (id int primary key, num varchar2 (12), regDate date) select * from test_hsj; -- insert test data insert into test_hsj values (1, '1', to_date ('2017-05-01 ', 'yyyy-MM-dd')