本文整理汇总了C#中IQueryContext.DropConstraint方法的典型用法代码示例。如果您正苦于以下问题：C# IQueryContext.DropConstraint方法的具体用法？C# IQueryContext.DropConstraint怎么用？C# IQueryContext.DropConstraint使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类IQueryContext的用法示例。
在下文中一共展示了IQueryContext.DropConstraint方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C#代码示例。
示例1: Evaluate
public override ITable Evaluate(IQueryContext context)
{
if (!context.UserCanAlterTable(TableName))
throw new InvalidAccessException(TableName);
var table = context.GetTable(TableName);
if (table == null)
throw new ObjectNotFoundException(TableName);
var tableInfo = table.TableInfo;
var newTableInfo = new TableInfo(tableInfo.TableName);
var checker = ColumnChecker.Default(context, TableName);
bool tableAltered = false;
bool markDropped = false;
for (int n = 0; n < tableInfo.ColumnCount; ++n) {
var column = tableInfo[n];
string columnName = column.ColumnName;
var columnType = column.ColumnType;
var defaultExpression = column.DefaultExpression;
if (Action.ActionType == AlterTableActionType.SetDefault &&
CheckColumnNamesMatch(context, ((SetDefaultAction) Action).ColumnName, columnName)) {
var exp = ((SetDefaultAction) Action).DefaultExpression;
exp = checker.CheckExpression(exp);
defaultExpression = exp;
tableAltered = true;
} else if (Action.ActionType == AlterTableActionType.DropDefault &&
CheckColumnNamesMatch(context, ((DropDefaultAction) Action).ColumnName, columnName)) {
defaultExpression = null;
tableAltered = true;
} else if (Action.ActionType == AlterTableActionType.DropColumn &&
CheckColumnNamesMatch(context, ((DropColumnAction) Action).ColumnName, columnName)) {
// Check there are no referential links to this column
var refs = context.GetTableImportedForeignKeys(TableName);
foreach (var reference in refs) {
CheckColumnConstraint(columnName, reference.ForeignColumnNames, reference.ForeignTable, reference.ConstraintName);
}
// Or from it
refs = context.GetTableForeignKeys(TableName);
foreach (var reference in refs) {
CheckColumnConstraint(columnName, reference.ColumnNames, reference.TableName, reference.ConstraintName);
}
// Or that it's part of a primary key
var primaryKey = context.GetTablePrimaryKey(TableName);
if (primaryKey != null)
CheckColumnConstraint(columnName, primaryKey.ColumnNames, TableName, primaryKey.ConstraintName);
// Or that it's part of a unique set
var uniques = context.GetTableUniqueKeys(TableName);
foreach (var unique in uniques) {
CheckColumnConstraint(columnName, unique.ColumnNames, TableName, unique.ConstraintName);
}
markDropped = true;
tableAltered = true;
}
var newColumn = new ColumnInfo(columnName, columnType);
if (defaultExpression != null)
newColumn.DefaultExpression = defaultExpression;
newColumn.IndexType = column.IndexType;
newColumn.IsNotNull = column.IsNotNull;
// If not dropped then add to the new table definition.
if (!markDropped) {
newTableInfo.AddColumn(newColumn);
}
}
if (Action.ActionType == AlterTableActionType.AddColumn) {
var col = ((AddColumnAction)Action).Column;
checker.CheckExpression(col.DefaultExpression);
var columnName = col.ColumnName;
var columnType = col.ColumnType;
// If column name starts with [table_name]. then strip it off
columnName = checker.StripTableName(TableName.Name, columnName);
if (tableInfo.IndexOfColumn(col.ColumnName) != -1)
throw new InvalidOperationException("The column '" + col.ColumnName + "' is already in the table '" + tableInfo.TableName + "'.");
var newColumn = new ColumnInfo(columnName, columnType) {
IsNotNull = col.IsNotNull,
DefaultExpression = col.DefaultExpression
};
newTableInfo.AddColumn(newColumn);
tableAltered = true;
}
if (Action.ActionType == AlterTableActionType.DropConstraint) {
string constraintName = ((DropConstraintAction)Action).ConstraintName;
int dropCount = context.DropConstraint(TableName, constraintName);
//.........这里部分代码省略.........