DescribeStatement <- ShowTables / ShowSelect / ShowAllTables / ShowQualifiedName

ShowSelect <- ShowOrDescribeOrSummarize SelectStatement
ShowAllTables <- ShowOrDescribe 'ALL' 'TABLES'
ShowQualifiedName <- ShowOrDescribeOrSummarize (BaseTableName / StringLiteral)?
ShowTables <- ShowOrDescribe 'TABLES' 'FROM' QualifiedName

ShowOrDescribeOrSummarize <- ShowOrDescribe / 'SUMMARIZE'
ShowOrDescribe <- 'SHOW' / 'DESCRIBE' / 'DESC'