11.Access中提供的字段数据类型总共有____种。 A.8 B.10 C.12 D.14 12.关于有效性规则属性正确的描述是: A.是指输入或删除记录时为维护表之间已定义的关系而必须遵循的规则; B.是用于对输入的记录、字段的数据的要求; C.就是指输入数据时最初的模认值; D
A.8
B.10
C.12
D.14
12.关于有效性规则属性正确的描述是:
A.是指输入或删除记录时为维护表之间已定义的关系而必须遵循的规则;
B.是用于对输入的记录、字段的数据的要求;
C.就是指输入数据时最初的模认值;
D.以上都不是;
13.Access显示数据表中数据的方式有:B
A.报表、页、窗体、查询;
B.表、页、窗体、查询;
C.报表、表、窗体、查询;
D.报表、页、窗体、表;
14.从“产品”表里查询出价格高于产品名称为“海天酱油”的产品的记录,此SQL语句为:
A.SELECT * FROM 产品WHERE 价格>海天酱油;
B.SELECT * FROM 产品WHERE 价格>(SELECT * FROM 产品WHERE 产品名称>’海天酱油’);
C.SELECT * FROM 产品WHERE EXISTS 产品名称=’海天酱油’);
D.SELECT * FROM 产品WHERE 价格>(SELECT 价格FROM 产品WHERE 产品名称=’海天酱油’);
15.下列语句正确的是:C
A.DELET FROM TABLENAME;
B.DETECT FROM TABLENAME;
C.DELETE FROM TABLENAME;
D.DELETE FIELD1 FROM TABLENAME
16.以下语句正确的是:B
A.UPDATA TABLENAME VALUES (FIELD_1='ABC');
B.UPDATE TABLENAME SET FIELD_1='ABC';
C.UPDTAE TABLE TableName SET FIELD_1='ABC';
D.UPDATA TABLE TableName VALUES FIELD_1='ABC'
17.下列语句正确的是:A
A.CREAT TABLE TABLENAME{ FIELD_1 NUMBER, FIELD_2 CHAR(10)};
B.CREAT TABLE TABLENAME( FIELD_1 NUMBER;
C.FIELD_2 CHAR(10));
D.CREATE TABLE TABLENAME( FIELD_1 NUMBER, FIELD_2 CHAR(10));CREAT TABLE TABLENAME( FIELD_1 NUMBER PK, FIELD_2 CHAR(10))
18.以下语句正确的是:B
A.DROPFROM TABLENAME;
BDROP TABLE TABLENAME;
C.DROP *FROM TABLE;
D.DROPE TABLENAME
19.以下语句正确的是:A
A.INSERT INTO TABLENAME(FIELD_1, FIELD_2) VALUES ('ABC',100);
B.INSERT TABLENAMESET FIELD_1='ABC';
C.INSERT TABLE TABLENAMEVALUES (FIELD_1='ABC');
D.INSET FIELD_1='ABC'FROM TABLENAME
20.找出所有在2003年9月8日借出的书籍?B
A.SELECT 姓名,书名 from 借阅信息where 借阅时间
B.SELECT 姓名,书名 from 借阅信息where 借阅时间 =#2003-9-8#;
C.SELECT 姓名,书名 from 借阅信息where 借阅时间
D.SELECT 姓名,书名 from 借阅信息where 借阅时间 >=#2003-9-8#

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.

The main reasons for poor MySQL query performance include not using indexes, wrong execution plan selection by the query optimizer, unreasonable table design, excessive data volume and lock competition. 1. No index causes slow querying, and adding indexes can significantly improve performance. 2. Use the EXPLAIN command to analyze the query plan and find out the optimizer error. 3. Reconstructing the table structure and optimizing JOIN conditions can improve table design problems. 4. When the data volume is large, partitioning and table division strategies are adopted. 5. In a high concurrency environment, optimizing transactions and locking strategies can reduce lock competition.

In database optimization, indexing strategies should be selected according to query requirements: 1. When the query involves multiple columns and the order of conditions is fixed, use composite indexes; 2. When the query involves multiple columns but the order of conditions is not fixed, use multiple single-column indexes. Composite indexes are suitable for optimizing multi-column queries, while single-column indexes are suitable for single-column queries.

To optimize MySQL slow query, slowquerylog and performance_schema need to be used: 1. Enable slowquerylog and set thresholds to record slow query; 2. Use performance_schema to analyze query execution details, find out performance bottlenecks and optimize.

MySQL and SQL are essential skills for developers. 1.MySQL is an open source relational database management system, and SQL is the standard language used to manage and operate databases. 2.MySQL supports multiple storage engines through efficient data storage and retrieval functions, and SQL completes complex data operations through simple statements. 3. Examples of usage include basic queries and advanced queries, such as filtering and sorting by condition. 4. Common errors include syntax errors and performance issues, which can be optimized by checking SQL statements and using EXPLAIN commands. 5. Performance optimization techniques include using indexes, avoiding full table scanning, optimizing JOIN operations and improving code readability.


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