mysql数据库应用实验训练

网站编辑2023-05-28 15:44:03539

以下是一个简单的 MySQL 数据库应用实验训练:

1. 创建一个表:

``` CREATE TABLE users ( idint, namestring, emailstring, phoneint, numberstring, datetimestring, birth_datestring, agestring), roles users ( username, password, age, age_gradestring, email_gradestring), role users ( username, password, age, age_gradestring, email_gradestring) );

rows = users.Tables.CREATE_EXISTS();

rows = rows.GetRows(); rows = rows.SUM(); // 计算表中所有字段的计数

for (i = 0; i < rows.Length; i++) { roles_ids = rows[i]; user_ids = rows[i].GetUsers(); number_ids = rows[i].GetDates(); role_ids = rows[i].GetRoles();

// 查找表中符合指定条件的键值对 if (roles_ids.Equals(i)) { break; }

// 创建表并插入数据 rows_insertion(row_insertion_row(roles_ids, user_ids, email_ids, birth_date, age)); }

// 删除表中所有不符合条件的键值对 rows_del(row_deletion_row(roles_ids));

return rows; ```

2. 创建一个 SQL 语句:

``` SELECT birth_date, age, email_name, phone, phone_grade, birth_date; FROM users; WHERE birth_date = NULL; // 创建表时不包含婚姻记录的键值对 GROUP BY birth_date; ```

3. 执行 SQL:

``` SELECT * FROM users WHERE birth_date = '2021-01-01'; ```

4. 查询表中符合条件的所有键值对

``` SELECT roles_ids, user_ids, phone_grade, birth_date; FROM users; WHERE birth_date = '2021-01-01'; // 创建表时不包含婚姻记录的键值对 GROUP BY roles_ids, user_ids, phone_grade, birth_date: FROM users;

ORDER BY user_ids, phone_grade, birth_date, birth_date: UNION; // 计算字段之间的交叉熵,并根据交叉熵进行排序,以优化查询性能。