("CREATE TABLE IF NOT EXISTS employees (" "id INTEGER PRIMARY KEY AUTOINCREMENT," "name VARCHAR(255)," "department_id INTEGER," "FOREIGN KEY (department_id) REFERENCES departments(id))") # 创建模型 model = QSqlRelationalTableModel(db=db) model.setTable('employees') model.setEditStrategy(...
ALTER TABLE EMPLOYEES ADD CONSTRAINT FK_FEP_ID FOREIGN KEY(DEPARTMENT_ID) REFERENCES DEPARTMENTS(DEPARTMENT_ID);UNIQUE constraintsA unique constraint is similar to a primary key constraint. It specifies that the values in a single column, or combination of columns, must be...
GL:I was part of an experiment atFast Company, where we wore sensor-packed badges that tracked our movements and conversations. One thing we learned is that the best-connected person in the office wasn’t the editor in chief or his deputies, but a new hire whose job touched multiple depa...
SQL Server DROP TABLE IF EXISTS Examples December 18, 2024 SQL Create Database Valuable Tutorial with T-SQL and SSMS December 11, 2024 Build Polymorphic Associations in SQL Server with Foreign Keys December 6, 2024 Subscribe Email(Required) ...
Usinglock_timeoutfor DDL commands is often enough. Must be able to handle failures, for example retry the DDL again. I'll be presenting this topic atPGDay CERNon 17th of January, if you're around, please come by and say hi! Stay tuned for the upcoming blog post. ...
REMAP TABLE hr.departments:example.new_departments, sh.channels:example.new_channels;示例2:从RMAN备份中恢复表SCOTT.EMP,SCOTT.DEPT,并以数据泵格式导出emp_dept_exp_dump.dat,并不进行表的导入 RECOVER TABLE SCOTT.EMP, SCOTT.DEPT UNTIL TIME 'SYSDATE-1' AUXILIARY DESTINATION '/tmp/oracle/recover' ...
Suppose you wanted to know how many departments have the same number of employees. What query could you use? Finding the number of employees by department name is pretty easy. We can use the following query to do so: SELECT GroupName, ...
CREATE TABLE departments_obj_t OF department_typ; The following statement creates object table salesreps with a user-defined object type, salesrep_typ:CREATE OR REPLACE TYPE salesrep_typ AS OBJECT ( repId NUMBER, repName VARCHAR2(64)); CREATE TABLE salesreps OF salesrep_typ; ...
The sample data contains simple employee information, including their names and departments. 3. Save the file and close nano. The file's location is required for the following step. Step 2: Import File to HDFS To use the file in Hive, import it into HDFS. Follow the steps below: ...
ALTER TABLE departments DROP CONSTRAINT pk_dept CASCADE; The CASCADE clause drops any foreign keys that reference the primary key. The following statement drops the unique key on the email column of the employees table: ALTER TABLE employees DROP UNIQUE (email); ...