当表只有FK时无法返回列表？

Question

When I choose a table when it doesn't have any Primary Key , my query returns nothing. So what's the problem in this query?

This is result when I have pk in my table:

And this is result when I haven't pk in my table:

Here is the query:

select 
    col.name as [Nom de Colone],
        typ.DATA_TYPE + CASE WHEN typ.DATA_TYPE IN('char', 'nchar', 'varchar', 'nvarchar', 'binary', 'varbinary')AND typ.CHARACTER_MAXIMUM_LENGTH > 0 THEN COALESCE('(' + 
        CONVERT(varchar, typ.CHARACTER_MAXIMUM_LENGTH) + ')','') ELSE '' END + CASE WHEN typ.DATA_TYPE IN('decimal', 'numeric') THEN COALESCE('(' + CONVERT(varchar, typ.NUMERIC_PRECISION) + ',' + CONVERT(varchar, typ.NUMERIC_SCALE) + ')','') 
    ELSE '' END AS [Type],
    CASE WHEN col.IS_NULLABLE = 0 THEN 'NOT ' ELSE '' END + 'NULL' AS Valeur,
    case when KU.COLUMN_NAME=col.name then cast(1 as bit) else cast(0 as bit) end as [PK],
    case when fk.object_id is not null then cast(1 as bit) else cast(0 as bit) end as [fk],
    case when pk_tab.name is not null then pk_tab.name else ''end as [Ref_Tab_FK],
    case when pk_col.name is not null then pk_col.name else ''end as [Ref_Col_FK]
from sys.tables tab 
    inner join sys.columns col  
        on col.object_id = tab.object_id 
    left outer join sys.foreign_key_columns fk_cols 
        on fk_cols.parent_object_id = tab.object_id and fk_cols.parent_column_id = col.column_id
    left outer join sys.foreign_keys fk  
        on fk.object_id = fk_cols.constraint_object_id left outer join sys.tables pk_tab 
        on pk_tab.object_id = fk_cols.referenced_object_id 
    left outer join sys.columns pk_col
        on pk_col.column_id = fk_cols.referenced_column_id and pk_col.object_id = fk_cols.referenced_object_id 
    inner join INFORMATION_SCHEMA.COLUMNS typ 
        on typ.COLUMN_NAME=col.name and tab.name=typ.TABLE_NAME 
    inner join INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS TC 
    on tc.TABLE_NAME=typ.TABLE_NAME and TC.CONSTRAINT_TYPE = 'PRIMARY KEY'
    INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KU
        ON TC.CONSTRAINT_TYPE = 'PRIMARY KEY'
        AND TC.CONSTRAINT_NAME = KU.CONSTRAINT_NAME     
where tab.name='TABLE_NAME' 
order by col.column_id

Answer 1

As you are putting INNER JOIN with PRIMARY KEY constraint, as given below, only the tables with PRIMARY KEY are returned in the result set.

    inner join INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS TC 
    on tc.TABLE_NAME=typ.TABLE_NAME and TC.CONSTRAINT_TYPE = 'PRIMARY KEY'
    INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KU
        ON TC.CONSTRAINT_TYPE = 'PRIMARY KEY'
        AND TC.CONSTRAINT_NAME = KU.CONSTRAINT_NAME     

If you change them to LEFT OUTER JOIN , you will get tables without PRIMARY KEY and just FOREIGN KEY also

    LEFT OUTER join INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS TC 
    on tc.TABLE_NAME=typ.TABLE_NAME and TC.CONSTRAINT_TYPE = 'PRIMARY KEY'
    LEFT OUTER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KU
        ON TC.CONSTRAINT_TYPE = 'PRIMARY KEY'
        AND TC.CONSTRAINT_NAME = KU.CONSTRAINT_NAME