[jira] [Commented] (FLINK-15553) Create table ddl support comment after computed column

["Jark Wu (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-15553?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17014077#comment-17014077 ] 

Jark Wu commented on FLINK-15553:
---------------------------------

cc [~danny0405]

> Create table ddl support  comment after computed column
> -------------------------------------------------------
>
>                 Key: FLINK-15553
>                 URL: https://issues.apache.org/jira/browse/FLINK-15553
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / API
>    Affects Versions: 1.10.0
>            Reporter: hailong wang
>            Priority: Major
>             Fix For: 1.11.0
>
>
> For now, we can define computed column in create table ddl, but we can not add comment after it just like regular table column, So we should support it,  it's grammar as follows:
> {code:java}
> col_name AS expr  [COMMENT 'string']
> {code}
> My idea is, we can introduce  class
> {code:java}
>  SqlTableComputedColumn{code}
> to wrap name, expression and comment,  And just get the element from it will be ok.
> As for parserImpls.ftl, it can be like as follows:
> {code:java}
> identifier = SimpleIdentifier()
> <AS>
> expr = Expression(ExprContext.ACCEPT_NON_QUERY)
> [ <COMMENT> <QUOTED_STRING> {
>     String p = SqlParserUtil.parseString(token.image);
>     comment = SqlLiteral.createCharString(p, getPos());
> }]
> {
>     SqlTableComputedColumn tableComputedColumn =
>         new SqlTableComputedColumn(identifier, expr, comment, getPos());
>     context.columnList.add(tableComputedColumn);
> }{code}
>  



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