-- Update statistics for index [IDX_TableName_ColumnName1_ColumnName2] on table [dbo].[TableName]

UPDATE STATISTICS [dbo].[TableName] [IDX_TableName_ColumnName1_ColumnName2];

-- Update statistics scanning whole table for index [IDX_TableName_ColumnName1_ColumnName2] on table [dbo].[TableName]

UPDATE STATISTICS [dbo].[TableName] [IDX_TableName_ColumnName1_ColumnName2] WITH FULLSCAN;