isCOBOL Evolve : Language Reference : Embedded SQL Statements : UPDATE
UPDATE
The UPDATE statement replaces the values of the specified columns with the values of the specified expressions for all rows of the table that satisfy the search condition.
General format
EXEC SQL [ AT Database ]
 
  [ FOR Iterations ]
 
  UPDATE Options SET { Column-Name = Column-Value } ... 
         [ WHERE { Search-Condition                                     } ]
                 { CURRENT OF Cursor-Name [ FOR ROW Row-Num OF ROWSET ] }
 
         [ RETURNING Field ... INTO HostVariable ... ]
 
END-EXEC
Syntax rules
1. Iterations can be either a host variable or a numeric literal. It specifies the number of rows to be processed.
2. Options is passed to the driver without further checks. Refer to the database documentation for detailed syntax. Syntax errors, if any, are returned at runtime.
3. Column-Name is a User-defined word, as defined in the Definitions section of the Preface of this document.
4. Column-Value is a host variable or a Nonnumeric Literal, as defined in the Definitions section of the Preface of this document.
5. Field is an alphanumeric literal.
6. Row-Num is a numeric literal or host variable.
7. Host-Variable is a host variable.
General rules
1. When Search-Condition is specified, only values in rows matching it are replaced.
2. The FOR clause limits the number of times the statement is executed when Search-Condition contains array host variables If you omit this clause,it executes the statement once for each component of the smallest array.
3. When Search-Condition is not specified, values of all rows are replaced.
4. Database identifies the active connection that will execute the query and must be previously defined using a Format 4 DECLARE statement.
5. CURRENT OF allows you to update the last fetched record in the active cursor.
When this syntax is used
o the statement associated to the cursor should not use "SELECT *" and
o the statement associated to the cursor should query from a single table.
Otherwise a "cursor is not updatable" error may occur.
6. FOR ROW n OF ROWSET specifies which row of the current rowset is to be updated. The corresponding row of the rowset is updated, and the cursor remains positioned on the current rowset.
7. The RETURNING clause allows you to receive the updated fields value into host variables.
Examples
Apply a discount to customers meeting a criteria
exec sql
     update customers
        set discount = 0.10
      where debt_amount < (credit_line * 0.25)
end-exec
Declare, open and fetch a cursor. Update records where the field cust-name is empty.
exec sql 
   declare cust_cur  cursor for select cust_code, cust_name from customers
end-exec               
 
exec sql 
   open cust_cur
end-exec     
 
perform until 1 = 2
   exec 
      sql fetch next cust_cur into :ws-cust-code, :ws-cust-name
   end-exec
 
   if ws-cust-name = space
      exec sql 
           update customers set cust_name = 'John' where current of cust_cur
      end-exec
   end-if
 
   if sqlcode = 100
      exit perform
   end-if
 
end-perform
 
exec sql 
   close cust_cur
end-exec