You can use the EGL replace statement
to update a row in a relational database.
Syntax
- entity
- Name of the entity, which is a variable based on an External type,
Handler type, or Record type. The values in that entity are used in
the corresponding SQL UPDATE statement. If you specify the SQL data
source but not an SQL statement, the following default is used:
UPDATE tableName
SET column_1 = ?,
column_2 = ?,
...
column_n = ?
WHERE
ID_column_1 = ? AND
ID_column_2 = ? AND
...
ID_column_n = ?
When an entity is used
from a SQL data source, the basic idea is as follows:
- A subset of entity fields are available. Those fields are updatable,
with values that are neither generated nor transient.
- The available entity fields are split into two categories. The
non-key fields are used in the SET clause. The key fields are not
used in the SET clause, but might be used in the WHERE clause.
- If the using clause is present, the values in that clause
are used in the WHERE clause. The using clause is an override.
- field
- A value of an EGL simple type that is compatible with the corresponding
database column.
The field values are assigned to the question
marks in the WHERE clause of the SQL UPDATE statement.
- SQLDataSource
- A variable of type SQLDataSource. The variable includes
connection details or references an EGL deployment descriptor entry
that provides access to the connection details.
If you issue a
prepared statement, the variable is optional and is ignored if present.
- SQLResultSet
- An SQL result set that was established by an open statement.
In this case, the Replace statement updates the current row.
An attempt to update the row a second time results in an exception.
- stmt
- A single SQL UPDATE statement, which is not required to end with
a semicolon but can. The statement format is as shown in the description
of entity.
You can use a prepared statement in place of #sql{stmt}.
If you need to update an ID column, your
replace statement
must use an explicit SQL statement with a
using clause that
includes simple values. For example, consider the following Record
type:
Record TwoKeys {@Table {name="MYTABLE"}}
id01 int {@Id};
id02 int {@Id};
aString string;
end
Here is an example use, when you want to change
the value of an ID column:
ds SQLDataSource?{@Resource{uri="binding:myEntry"}};
row TwoKeys;
replace row to ds with
#sql{
update MYTABLE
set aString = ?, id02 = ?
where
id01 = ? and id02 = ?
}
using
row.aString,
10,
row.id01,
row.id02;
Compatibility
Table 1. Compatibility
Target |
Issue |
Java |
No issues |
JavaScript |
Database access is not supported in JavaScript.
|