PL/SQL number型数据
number( ,)
精度p取值范围1~38
有效位s取值范围-84~127
最高整数位数=p-s
s正数,小数点右边指定位置开始四舍五入
s负数,小数点左边指定位置开始四舍五入
s是0或者未指定,四舍五入到最近整数
当p小于s时候,表示数字是绝对值小于1的数字,且从小数点右边开始的前s-p 位必须是0,保留s位小数。
--num_test start------------------------------------------------
Connected to Oracle9i Enterprise Edition Release 9.0.1.1.1
Connected as aspire
SQL>
SQL> SET linesize 1000;
SQL> CREATE TABLE hjm_num_test
2 (a NUMBER,
3 b NUMBER(5,2),
4 c NUMBER(5,-2),
5 d NUMBER(5,0),
6 e NUMBER(5),
7 f NUMBER(2,5));
Table created
SQL> INSERT INTO hjm_num_test
2 (a,b,c,d,e,f) VALUES(123.3333,123.3333,123.3333,123.3333,123.3333,-0.0003);
1 row inserted
SQL> INSERT INTO hjm_num_test
2 (a,b,c,d,e,f) VALUES(197.9333,197.9333,197.9333,197.9333,197.9333,0.00012567);
1 row inserted
SQL> COMMIT;
Commit complete
SQL> SELECT * FROM hjm_num_test;
(在pl/sql dev sql窗口显示)
--num_test end--------------------------------------------------------
似乎结果很正确,可是现在出来一个问题,当我不在pl/sql dev窗口运行,我在isqlplus中运行,结果就有点不一样了,注意,第1行的F列:
(在isqlplus中显示)
它舍去了末尾的0!在sqlplus下测试也是同样的效果。
不过本人的意向应该是还是保留那个0的,因为number(2,5)它毕竟指定了有效位是5位。

MySQL'sBLOBissuitableforstoringbinarydatawithinarelationaldatabase,whileNoSQLoptionslikeMongoDB,Redis,andCassandraofferflexible,scalablesolutionsforunstructureddata.BLOBissimplerbutcanslowdownperformancewithlargedata;NoSQLprovidesbetterscalabilityand

ToaddauserinMySQL,use:CREATEUSER'username'@'host'IDENTIFIEDBY'password';Here'showtodoitsecurely:1)Choosethehostcarefullytocontrolaccess.2)SetresourcelimitswithoptionslikeMAX_QUERIES_PER_HOUR.3)Usestrong,uniquepasswords.4)EnforceSSL/TLSconnectionswith

ToavoidcommonmistakeswithstringdatatypesinMySQL,understandstringtypenuances,choosetherighttype,andmanageencodingandcollationsettingseffectively.1)UseCHARforfixed-lengthstrings,VARCHARforvariable-length,andTEXT/BLOBforlargerdata.2)Setcorrectcharacters

MySQloffersechar, Varchar, text, Anddenumforstringdata.usecharforfixed-Lengthstrings, VarcharerForvariable-Length, text forlarger text, AndenumforenforcingdataAntegritywithaetofvalues.

Optimizing MySQLBLOB requests can be done through the following strategies: 1. Reduce the frequency of BLOB query, use independent requests or delay loading; 2. Select the appropriate BLOB type (such as TINYBLOB); 3. Separate the BLOB data into separate tables; 4. Compress the BLOB data at the application layer; 5. Index the BLOB metadata. These methods can effectively improve performance by combining monitoring, caching and data sharding in actual applications.

Mastering the method of adding MySQL users is crucial for database administrators and developers because it ensures the security and access control of the database. 1) Create a new user using the CREATEUSER command, 2) Assign permissions through the GRANT command, 3) Use FLUSHPRIVILEGES to ensure permissions take effect, 4) Regularly audit and clean user accounts to maintain performance and security.

ChooseCHARforfixed-lengthdata,VARCHARforvariable-lengthdata,andTEXTforlargetextfields.1)CHARisefficientforconsistent-lengthdatalikecodes.2)VARCHARsuitsvariable-lengthdatalikenames,balancingflexibilityandperformance.3)TEXTisidealforlargetextslikeartic

Best practices for handling string data types and indexes in MySQL include: 1) Selecting the appropriate string type, such as CHAR for fixed length, VARCHAR for variable length, and TEXT for large text; 2) Be cautious in indexing, avoid over-indexing, and create indexes for common queries; 3) Use prefix indexes and full-text indexes to optimize long string searches; 4) Regularly monitor and optimize indexes to keep indexes small and efficient. Through these methods, we can balance read and write performance and improve database efficiency.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

Dreamweaver CS6
Visual web development tools
