SQL四舍五入保留浮点数的十位有效数字 无 DECLARE @execsql NVARCHAR(1024)SET @execsql =N'SELECT CAST('+CAST(125.365412354 AS NVARCHAR(20)) +N' AS NUMERIC (20,'+STR(10-CEILING(LOG10(125.365412354)))+N'))'EXEC SP_EXECUTESQL @execsql /*ROUND?(?nu
SQL四舍五入保留浮点数的十位有效数字DECLARE @execsql NVARCHAR(1024) SET @execsql =N'SELECT CAST('+CAST(125.365412354 AS NVARCHAR(20)) +N' AS NUMERIC (20,'+STR(10-CEILING(LOG10(125.365412354)))+N'))' EXEC SP_EXECUTESQL @execsql
/*ROUND?(?numeric_expression?,?length?[?,function?]?) function?必须为?tinyint、smallint??或?int。 如果省略?function?或其值为?0(默认值),则将舍入?numeric_expression。 如果指定了0以外的值,则将截断?numeric_expression。*/ SELECT?ROUND(150.45648,?2);--保留小数点后两位,需要四舍五入 SELECT?ROUND(150.45648,?2,?0);--保留小数点后两位,0为默认值,表示进行四舍五入 SELECT?ROUND(150.45648,?2,?1);--保留小数点后两位,不需要四舍五入,这里除0以外都是有同样的效果 SELECT?ROUND(150.45648,?2,?2);--保留小数点后两位,不需要四舍五入,这里除0以外都是有同样的效果 --150.46000 --150.45000 --150.45000 --150.45000

MySQL's position in databases and programming is very important. It is an open source relational database management system that is widely used in various application scenarios. 1) MySQL provides efficient data storage, organization and retrieval functions, supporting Web, mobile and enterprise-level systems. 2) It uses a client-server architecture, supports multiple storage engines and index optimization. 3) Basic usages include creating tables and inserting data, and advanced usages involve multi-table JOINs and complex queries. 4) Frequently asked questions such as SQL syntax errors and performance issues can be debugged through the EXPLAIN command and slow query log. 5) Performance optimization methods include rational use of indexes, optimized query and use of caches. Best practices include using transactions and PreparedStatemen

MySQL is suitable for small and large enterprises. 1) Small businesses can use MySQL for basic data management, such as storing customer information. 2) Large enterprises can use MySQL to process massive data and complex business logic to optimize query performance and transaction processing.

InnoDB effectively prevents phantom reading through Next-KeyLocking mechanism. 1) Next-KeyLocking combines row lock and gap lock to lock records and their gaps to prevent new records from being inserted. 2) In practical applications, by optimizing query and adjusting isolation levels, lock competition can be reduced and concurrency performance can be improved.

MySQL is not a programming language, but its query language SQL has the characteristics of a programming language: 1. SQL supports conditional judgment, loops and variable operations; 2. Through stored procedures, triggers and functions, users can perform complex logical operations in the database.

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

MySQL is an open source relational database management system suitable for data storage, management, query and security. 1. It supports a variety of operating systems and is widely used in Web applications and other fields. 2. Through the client-server architecture and different storage engines, MySQL processes data efficiently. 3. Basic usage includes creating databases and tables, inserting, querying and updating data. 4. Advanced usage involves complex queries and stored procedures. 5. Common errors can be debugged through the EXPLAIN statement. 6. Performance optimization includes the rational use of indexes and optimized query statements.

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

InnoDB's lock mechanisms include shared locks, exclusive locks, intention locks, record locks, gap locks and next key locks. 1. Shared lock allows transactions to read data without preventing other transactions from reading. 2. Exclusive lock prevents other transactions from reading and modifying data. 3. Intention lock optimizes lock efficiency. 4. Record lock lock index record. 5. Gap lock locks index recording gap. 6. The next key lock is a combination of record lock and gap lock to ensure data consistency.


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