private async Task <string> GetNullableColumnHasValueQueryCore(Identifier tableName, Identifier columnName) { var quotedTableName = Dialect.QuoteName(Identifier.CreateQualifiedIdentifier(tableName.Schema, tableName.LocalName)); var quotedColumnName = Dialect.QuoteIdentifier(columnName.LocalName); var filterSql = $"select * from { quotedTableName } where { quotedColumnName } is not null"; var sql = $"select case when exists ({ filterSql }) then 1 else 0 end as dummy"; var suffix = await _fromQuerySuffixAsync.ConfigureAwait(false); return(suffix.IsNullOrWhiteSpace() ? sql : sql + " from " + suffix); }