A primary key in ORACLE 11g became nullable - Stack Overflow
stackoverflow.com › 38652341 › a-prim...
Jul 29, 2016 · I came across this issue in Oracle 12g r 2. The desc MY_TABLE did not show the NOT NULL for a column that did have a NOT NULL constraint.
People also ask
Can a primary key be nullable?
Primary key constraints
NULL values are not allowed. If the column(s) contain NULL values, the system will not add the primary key constraint.
Can primary key have NULL values in Oracle?
The primary key is the minimum set of traits that distinguishes any row of a table. It cannot have NULL and duplicate values. The primary key is used to add integrity to the table.
How to change NULL to blank in Oracle?
NVL lets you replace null (returned as a blank) with a string in the results of a query. If expr1 is null, then NVL returns expr2 . If expr1 is not null, then NVL returns expr1 .
How to insert null value in primary key column?
Primary keys must always have a value, so they cannot be NULL. You are trying to insert a NULL value into a column that has a foreign key constraint. Foreign key constraints require that the value in the column must exist in the referenced table.