private VxSchemaErrors ApplyChangedColumn(VxSchemaTable table,
VxSchemaTableElement oldelem, VxSchemaTableElement newelem,
VxSchemaError expected_err, VxPutOpts opts)
{
VxSchemaErrors errs = new VxSchemaErrors();
log.print("Altering {0}\n", newelem.ToString());
bool destructive = (opts & VxPutOpts.Destructive) != 0;
string colname = newelem.GetParam("name");
// Remove any old default constraint; even if it doesn't change, it
// can get in the way of modifying the column. We'll add it again
// later if needed.
if (oldelem.HasDefault())
{
string defquery = wv.fmt("ALTER TABLE [{0}] DROP CONSTRAINT {1}",
table.name, table.GetDefaultDefaultName(colname));
log.print("Executing {0}\n", defquery);
dbi.execute(defquery);
}
bool did_default_constraint = false;
// Don't try to alter the table if we know it won't work.
if (expected_err == null)
{
string query = wv.fmt("ALTER TABLE [{0}] ALTER COLUMN {1}",
table.name, table.ColumnToSql(newelem, false));
log.print("Executing {0}\n", query);
dbi.execute(query);
}
else
{
// Some table attributes can't be changed by ALTER TABLE,
// such as changing identity values, or data type changes that
// would truncate data. If the client has set the Destructive
// flag though, we can try to drop and re-add the column.
if (destructive)
{
log.print("Alter column would fail, dropping and adding.\n");
log.print("Expected error message: {0} ({1})\n",
expected_err.msg, expected_err.errnum);
string delquery = wv.fmt("ALTER TABLE [{0}] " +
"DROP COLUMN [{1}]",
table.name, colname);
// We need to include the default value here (the second
// parameter to ColumnToSql), otherwise adding a column to a
// table with data in it might not work.
string addquery = wv.fmt("ALTER TABLE [{0}] ADD {1}",
table.name, table.ColumnToSql(newelem, true));
log.print("Executing {0}\n", delquery);
dbi.execute(delquery);
log.print("Executing {0}\n", addquery);
dbi.execute(addquery);
did_default_constraint = true;
}
else
{
// Error 515: Can't modify a column because it contains nulls
// and the column requires non-nulls.
if (expected_err.errnum == 515)
{
log.print("Couldn't modify column due to null " +
"restriction. Making column nullable.\n");
var nullable = GetNullableColumn(newelem);
string query = wv.fmt("ALTER TABLE [{0}] ALTER COLUMN {1}",
table.name, table.ColumnToSql(nullable, false));
log.print("Executing {0}\n", query);
dbi.execute(query);
}
else
{
log.print("Can't alter table and destructive flag " +
"not set. Giving up.\n");
string key = table.key;
string errmsg = wv.fmt("Refusing to drop and re-add " +
"column [{0}] when the destructive option " +
"is not set. Error when altering was: '{1}'",
colname, expected_err.msg);
errs.Add(key, new VxSchemaError(key, errmsg, -1));
}
}
}
// No errors so far, let's try to add the new default values if we
// didn't do it already.
// FIXME: Check for actual errors, don't care about warnings.
if (errs.Count == 0 && newelem.HasDefault() && !did_default_constraint)
{
string defquery = wv.fmt("ALTER TABLE [{0}] ADD CONSTRAINT {1} " +
"DEFAULT {2} FOR {3}",
table.name, table.GetDefaultDefaultName(colname),
newelem.GetParam("default"), colname);
log.print("Executing {0}\n", defquery);
dbi.execute(defquery);
}
if (errs.Count != 0)
log.print("Altering column had errors: " + errs.ToString());
return errs;
}
// Create a new table element that allows nulls
private VxSchemaTableElement GetNullableColumn(VxSchemaTableElement elem)
{
var nullable = new VxSchemaTableElement(elem.elemtype);
foreach (var kvp in elem.parameters)
if (kvp.Key == "null")
nullable.AddParam("null", "1");
else
nullable.AddParam(kvp.Key, kvp.Value);
return nullable;
}
private void DropTableColumn(VxSchemaTable table, VxSchemaTableElement col)
{
string colname = col.GetParam("name");
if (col.HasDefault())
{
string defquery = wv.fmt("ALTER TABLE [{0}] " +
"DROP CONSTRAINT {1}",
table.name, table.GetDefaultDefaultName(colname));
dbi.execute(defquery);
}
string query = wv.fmt("ALTER TABLE [{0}] DROP COLUMN [{1}]",
table.name, colname);
dbi.execute(query);
}
private VxSchemaError PutSchemaTableIndex(string key, VxSchemaTable table,
VxSchemaTableElement elem)
{
string query = "";
if (elem.elemtype == "primary-key")
query = table.PrimaryKeyToSql(elem);
else if (elem.elemtype == "index")
query = table.IndexToSql(elem);
else
return new VxSchemaError(key, wv.fmt(
"Unknown table element '{0}'.", elem.elemtype), -1);
try
{
if (query != "")
dbi.execute(query);
}
catch (SqlException e)
{
return new VxSchemaError(key, e);
}
return null;
}
