Miscellaneous

How do you identify constraints in a table?

How do you identify constraints in a table?

1 Answer

  1. SELECT * FROM user_cons_columns. WHERE table_name = ”;
  2. SELECT * FROM user_constraints. WHERE table_name = ” AND constraint_name = ”;
  3. all_cons_columns.
  4. all_constraints.
  5. AND owner = ”

Where are Oracle table comments stored?

One thing I don’t like is the ability to see table comments. To find this information you need to click on the table inside the table view (“Connections” > #MY_CON2# > Tables), then on tab: “Details”, scroll to column “Comments” and finally double click on the comment field to see all details. select TABLE_NAME, K.

What is comment on table in Oracle?

Use the COMMENT statement to add a comment about a table, view, materialized view, or column into the data dictionary. To drop a comment from the database, set it to the empty string ‘ ‘. Oracle Database Reference for information on the data dictionary views that display comments.

How do you comment in Oracle?

Comments

  1. Begin the comment with a slash and an asterisk (/*). Proceed with the text of the comment. This text can span multiple lines. End the comment with an asterisk and a slash (*/).
  2. Begin the comment with — (two hyphens). Proceed with the text of the comment. This text cannot extend to a new line.

What are the constraint types in Oracle?

Types of Oracle Constraints

  • NOT NULL. If we just add a column, by default the column is allowed to hold NULL values but in case there is a requirement that the column should not hold any NULL values.
  • UNIQUE.
  • PRIMARY KEY.
  • FOREIGN KEY Constraints.
  • CHECK Constraint.

Which clause limits or filters the records of aggregated queries?

Discussion: To filter records according the given number of rows in the group, use the HAVING clause. It filters rows using in a condition aggregate function like COUNT.

How do I comment in a stored procedure?

To create line comments you just use two dashes “–” in front of the code you want to comment. You can comment out one or multiple lines with this technique. In this example the entire line is commented out.

How do I view comments in a table?

View comments You will see table comments in Remarks column in list of objects and when you select table you will see column comments in Remarks column in Columns tab.

How do you comment in SQL?

You can comment out or uncomment a single line of code in an SQL statement, multiple adjacent lines of code, a complete SQL statement, or multiple adjacent SQL statements. The syntax for a comment in a line of SQL code is a double hyphen ( — ) at the beginning of the line.

What are table constraints?

Constraints are the rules enforced on the data columns of a table. These are used to limit the type of data that can go into a table. This ensures the accuracy and reliability of the data in the database. PRIMARY Key − Uniquely identifies each row/record in a database table.

What are the table level constraints?

Table-level constraints refer to one or more columns in the table. Table-level constraints specify the names of the columns to which they apply. Table-level CHECK constraints can refer to 0 or more columns in the table.

How to list all check constraints in Oracle Database?

Scope of rows: (A) all check constraints on tables accessible to the current user in Oracle database, (B) all check constraints on tables in Oracle database There are no comments. Click here to write the first comment.

How to view the comments in Oracle Database?

If you omit schema, then Oracle Database assumes the table, view, or materialized view is in your own schema. You can view the comments on a particular table or column by querying the data dictionary views USER_TAB_COMMENTS, DBA_TAB_COMMENTS, or ALL_TAB_COMMENTS or USER_COL_COMMENTS, DBA_COL_COMMENTS, or ALL_COL_COMMENTS.

How to add a comment to a table in SQL?

Use the COMMENTstatement to add a comment about a table, view, materialized view, or column into the data dictionary. To drop a comment from the database, set it to the empty string ‘ ‘. See Also: “Comments”for more information on associating comments with SQL statements and schema objects.

What happens when you add a constraint to the Ref column?

If you add a referential integrity constraint to an existing REF column that is already scoped, then the referenced table must be the same as the scope table of the REF column. If you later drop the referential integrity constraint, then the REF column will remain scoped to the referenced table.