consistent=y full=y buffer=64000But when we import this data we have too many errors, such as "ORA-2264: name already used by an existing constraint." We have found out that when we make a new user in a new database then some tables exist; in this case when we import data it crashes with the existing constraint. Please help us to find the solution.
You did not list your import parameters so I am unsure as to your exact problem.
When you import objects into a schema, those objects to be imported must not have the same name as other objects in the schema. In your case, you are experiencing the ORA-2264 error which means other constraints in the schema have this same name. As a matter of good practice, I always put my table name and the constraint type and sometimes the affected columns in my constraint name. This way, I will not have conflicts with two constraints trying to use the same name. For example, a PK constraint on the EMP table will be named EMP_PK. A unique constraint on the SSN column of the EMP table will be named EMP_SSN_UK. A Foreign Key constraint from EMP to DEPT will be named EMP_DEPT_FK. A NOT NULL constraint on the NAME column of the EMP table will be named EMP_NAME_NN. Since I cannot have two tables named EMP, similar constraints will not have the same name because I have followed a convention to ensure this does not happen.
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