use
SQL WHERE clause (w3school.com.cn)
-- Notes
/*
1. SQL can be divided into two parts: Data Manipulation Language (DML) and Data Definition Language (DDL).
Query and update instructions make up the DML part of SQL:
SELECT - get data from a database table
UPDATE - update data in a database table
DELETE - delete data from a database table
INSERT INTO - insert data into a database table Data
Definition Language (DDL) section gives us the ability to create or delete tables. We can also define indexes (keys), specify links between tables, and impose constraints between tables.
CREATE DATABASE - create a new database
ALTER DATABASE - modify a database
CREATE TABLE - create a new table
ALTER TABLE - alter (alter) a database table
DROP TABLE - drop a table
CREATE INDEX - create an index (search key)
DROP INDEX - drop an index
*/
select * from "TS_DATA1_ZTL";
-- In the table, may contain duplicate values. The keyword DISTINCT is used to return uniquely distinct values
SELECT DISTINCT T011 from TS_DATA1_ZTL;
--Obviously the keyword DISTINCT can only be used to return a field
SELECT DISTINCT T011, T001 from TS_DATA1_ZTL;
1. Windows, download the Oracle19c database from the official website
Oracle official download link:
Database Software Downloads | Oracle
But to download, you need to register an Oracle account
A system error occurred and the mailbox cannot be received
So this little friend ca n't receive the oracle registration email or can't log in.
Then start the download: zip
But Microsoft edge is slow to download? How to increase download speed?
If you are using the new version of Edge with the latest Chromiun kernel, enter edge://flags , search for Parallel downloading in the search box in the upper right corner, select Enable, and restart. From 20KB/s to:
2. Installation and configuration
This little partner Oracle19c installation configuration tutorial_oracle19c installation tutorial_Rain period's blog-CSDN blog
Navicat connects to oracle (128 messages) Oracle19c installation, basic configuration tutorial (super detailed)_Bald Cloakman's Blog-CSDN Blogs
3. Record the problems encountered in the process of using oracle:
1.
It was fine 10 minutes ago; now when you log in to the database, you will report this error directly
After querying, I found that the reason for this problem is due to insufficient table space. Baidu has a bunch of sql to expand the size of the table space.
ORA-00604: error occurred at recursive SQL level 1 error refers to the internal SQL statement execution failure
ORA-01653: unable to extend table SYS.AUD$ by 8192 in tablespace SYSTEM means the tablespace is full
But still don't know how to do it. . . . . .
PL/SQL cannot log in, how to write sql to expand the size of the table space
You can directly enter sql on the server, log in to the server where oracle is installed ,
ORA-00604: error occurred at recursive SQL level 1ORA-01653: unable to extend table SYS.AUD$ by 8192
2. Oracle views and indexes:
create view
View data through views:
Create an index:
CREATE INDEX IDX_7DA9DA58 ON TS_Stockinfo_ztl
(
IsValid,
TSDA
);
3. Market data: There are a lot of market data every day, how to import them? ?
excel method
..........
Query consideration speed
oracle link missing,
oracle delete data in the table
Three ways to delete data in Oracle
Delete table (record and structure) statement delete - truncate - drop
drop command
drop table table name;
For example: delete the student table (student)
drop table student;Note:
1. Using drop to delete table data will not only delete the data in the table, but also delete the structure!
truncate command
truncate table table name;
For example: delete the student table (student)
truncate table student;Note:
1. Use truncate to delete table data, just delete the data in the table, the table structure will not be deleted!
2. When deleting the data of the entire table, the process is that the system deletes the data at one time, which is more efficient.
3. truncate deletes to free up space
delete command
delete from table name;
For example: delete the student table (student)
delete from student;Note:
1. Use delete to delete table data, just delete the data in the table, the table structure will not be deleted!
2. Although the data in the entire table is also deleted, the process is to delete the system line by line, which is less efficient than truncate.
3. Delete delete does not release space
renew:
update TS_ZTL5 set tsda = sysdate where isvalid = 1
UPDATE TS_ZTL5 set INDEXID = 'SH000300ZTL' WHERE ISVALID = 1
Unlucky, unlucky, I accidentally deleted the d drive when I called the company function today, all the software needs to be downloaded again, and then there are only 3 folders left in oracle (including bin), in the spirit of giving it a try, decompress the installation package again to the original path,
But: now the oracle library in the company's test server can be used (in fact, navicat connects to the server database, and there is no need to download oracle locally)
local not listening
How can this be done without deleting the oracle, and reconfigure the monitoring?
The oracle installation directory is deleted, what should I do?_Baidu Know(baidu.com)