Tag：oracle
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Time：2020-7-8
Oracle flash back technologyHere, four kinds of flash back technologies are sorted out, and Oracle flash back technology is summarized. summary: Flashback technology is a part of Oracle’s powerful database backup and recovery mechanism. When there is a logical error in the database, flashback technology can provide fast and minimal loss recovery (most of the […]
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Time：2020-7-7
The difference between call and exec in Oracle Today, I used Oracle to do the project. I found it interesting in the process of doing the project. I found some information and shared it with you In sqlplus: Tools provided by third parties (e.g. plsqldev) Summary: Exec is a command of sqlplus and can only […]
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Time：2020-7-3
First of all, when using subqueries, you should pay attention to the following: subqueries can be nested in multiple layers and subqueries need to be surrounded by parentheses (). Let’s take a look at the details. Basic introduction 1. Where: a subquery generally returns a single row, a single column, a single column, multiple columns, […]
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Time：2020-6-25
summary The procedure and function (usually called subprogram) in PL / SQL is a special type of PL / SQL block. This kind of subprogram can be stored in the database in the form of compilation and called for the subsequent block. Same point: program to complete specific functions Difference: use return statement to return […]
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Time：2020-6-24
Many students seem to know little about SQL optimization. Recently, they summarized the following 34 items for reference only. (1) Select the most efficient table name order (only valid in rule-based optimizers): The Oracle parser processes the table names in the from clause from right to left. The last table written in the from clause […]
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Time：2020-6-23
1. During data migration, users have the right to modify the database, create and delete tablespaces, etc For example: select * from dba_tab_privs where grantee=’SCOT’; —View Scott permissions (sys user login) The results are: select * from dba_role_privs where grantee=’SCOT’; –View Scott role The results are: (1) If the user is locked, unlock the table […]
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Time：2020-6-20
I saw an official Oracle installation document of RedHat two days ago, which describes the modification of Linux kernel parameters very clearly. Before installing Oracle, in addition to checking whether the hardware and software of the operating system meet the installation requirements, one of the key points is to modify the kernel parameters, the most […]
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Time：2020-6-19
It is very convenient to use shell under Linux and UNIX, if it can be implemented in combination with planned tasks under Windows Environment 1. Create the backup directory D: \ backup, and create the batch command Bak.bat , script backup exp user/[email protected] DIRECT=Y BUFFER=100000 FILE=D:\backup\scdd%date:~0,10% OWNER=(‘scdd’) LOG=D:\backup\data.log forfiles /p “D:\backup” /s /m *.dmp /d […]
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Time：2020-6-18
I won’t say what happened, but I will focus on the following: Computer – > properties – > advanced system settings – > Advanced – > environment variables 1) Edit path in system variable, select all and copy all the paths to the text document; 2) Create a new system variable named path1, cut all […]
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Time：2020-6-17
According to the characteristics of Oracle database and the tools provided, the main methods are as follows: Using logical backup to lose data table using import tool Using physical backup to restore data files and incomplete recovery Using DBMS_ Recovery of LOGMNR package from redo log file Using flashback to recover data premise In order […]
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Time：2020-6-17
Oracle SQL Developer It is a very powerful and open-source SQL development tool. The popular databases in front of the market support connection. You can directly connect Oracle and MySQL in SQL developer. You can put Navicat and PLSQL tools aside for a while, and then step into the main topic,First, we go to the […]
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Time：2020-6-16
I don’t need to talk about much nonsense. I’ll post the code for you. The specific code is as follows: CREATE OR REPLACE FUNCTION f_get_param( IN_PARAM IN VARCHAR2, IN_FLAG IN VARCHAR2) RETURN VARCHAR2 IS RESULT VARCHAR2(500); v_leng NUMBER; v_left NUMBER; v_right NUMBER; v_param VARCHAR2(200); v_param1 VARCHAR2(200); BEGION RESULT := ”; v_param:=IN_PARAM; v_leng := LENGTH(v_param); v_left […]
