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I have a table 'test' having a column 'Name' with no constraints. I need to ALTER this column by giving it a UNIQUE constraint. How should I do it?
Should I use op.alter_column('???') or create_unique_constraint('???')? Isn't create_unique_constraint for new column and not for existing one?
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When we will add a UNIQUE constraint on the same column multiple times then MySQL will create the index on that column for a number of times we have added the UNIQUE constraint.
The syntax for creating a unique constraint using an ALTER TABLE statement in MySQL is: ALTER TABLE table_name ADD CONSTRAINT constraint_name UNIQUE (column1, column2, ... column_n); table_name.
The UNIQUE constraint ensures that all values in a column are different. Both the UNIQUE and PRIMARY KEY constraints provide a guarantee for uniqueness for a column or set of columns.
To add, you'd need: https://alembic.sqlalchemy.org/en/latest/ops.html#alembic.operations.Operations.create_unique_constraint
from alembic import op op.create_unique_constraint('uq_user_name', 'user', ['name'], schema='my_schema') To drop, you'd need: https://alembic.sqlalchemy.org/en/latest/ops.html#alembic.operations.Operations.drop_constraint
op.drop_constraint('uq_user_name', 'user', schema='my_schema') If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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