MySQL Select 语句使用相同的表和列但别名不同的名称

Question

I am working on a site I have inherited and I do not know MySQL that well. I have copied this from an Access query and converted it to MySQL but I get an error:

Unknown column 'CornerAbutTo1' in 'field list'

This is my converted statement:

SELECT tblMasonry.Site, tblMasonry.MUNum, trelMUSU.SUNum,
        trelMUFe.FeNum, tlkpFeTyp.FeTyp, tlkpCardinalDirection.Dir,
        tblMasonry.Dir, tlkpCardinalDirection.Sort, tlkpMasonryTyp.MasonryTyp,
        tblMasonry.Face, tblMasonry.HtMax, tblMasonry.HtMin,
        tblMasonry.NumCourses, tblMasonry.Complete, tblMasonry.HtInf,
        tblMasonry.PctPecked, tblMasonry.PctGround, tblMasonry.PctFlaked,
        tblMasonry.PctUnshp, tblMasonry.ShapingComm, tblMasonry.PctBlock,
        tblMasonry.PctTabular, tblMasonry.PctIrreg, tblMasonry.ShapesComm,
        tblMasonry.Foundation, tblMasonry.Chinking, tblMasonry.Mortar,
        tblMasonry.PctPlaster, tblMasonry.Material, tblMasonry.Coursing,
        tblMasonry.CrossSec, tblMasonry.Comm, 
        tlkpCardinalDirection_1.Dir AS CornerAbutTo1,
        tlkpCardinalDirection_2.Dir AS CornerAbutTo2,
        tlkpCardinalDirection_3.Dir AS CornerAbutBy1,
        tlkpCardinalDirection_4.Dir AS CornerAbutBy2,
        tlkpCardinalDirection_5.Dir AS CornerTiedTo1,
        tlkpCardinalDirection_6.Dir AS CornerTiedTo2,
CASE
WHEN CornerAbutTo1 AND CornerAbutTo2 IS NULL THEN 'no data'
WHEN CornerAbutTo1 IS NOT NULL AND CornerAbutTo2 IS NULL THEN CornerAbutTo1
ELSE CONCAT( CornerAbutTo1, ' ', 'and', ' ', CornerAbutTo2)
END AS CornersAbutTo,

CASE
WHEN CornerAbutBy1 AND CornerAbutBy2 IS NULL THEN 'no data'
WHEN CornerAbutBy1 IS NOT NULL AND CornerAbutBy2 IS NULL THEN CornerAbutBy1
ELSE CONCAT( CornerAbutBy1, ' ', 'and', ' ', CornerAbutBy2)
END AS CornersAbutBy,
    
CASE
WHEN CornerTiedTo1 AND CornerTiedTo2 IS NULL THEN 'no data'
WHEN CornerTiedTo1 IS NOT NULL AND CornerTiedTo2 IS NULL THEN CornerTiedTo1
ELSE CONCAT( CornerTiedTo1, ' ', 'and', ' ', CornerTiedTo2)
END AS CornersTiedTo

FROM ((tlkpMasonryTyp RIGHT JOIN (((((((tblMasonry LEFT JOIN tlkpCardinalDirection ON tblMasonry.Dir = tlkpCardinalDirection.DirCode)
        LEFT JOIN tlkpCardinalDirection AS tlkpCardinalDirection_1 ON tblMasonry.CornerAbutTo_1 = tlkpCardinalDirection_1.DirCode)
        LEFT JOIN tlkpCardinalDirection AS tlkpCardinalDirection_2 ON tblMasonry.CornerAbutTo_2 = tlkpCardinalDirection_2.DirCode)
        LEFT JOIN tlkpCardinalDirection AS tlkpCardinalDirection_3 ON tblMasonry.CornerAbutBy_1 = tlkpCardinalDirection_3.DirCode)
        LEFT JOIN tlkpCardinalDirection AS tlkpCardinalDirection_4 ON tblMasonry.CornerAbutBy_2 = tlkpCardinalDirection_4.DirCode)
        LEFT JOIN tlkpCardinalDirection AS tlkpCardinalDirection_5 ON tblMasonry.CornerTiedTo_1 = tlkpCardinalDirection_5.DirCode)
        LEFT JOIN tlkpCardinalDirection AS tlkpCardinalDirection_6 ON tblMasonry.CornerTiedTo_2 = tlkpCardinalDirection_6.DirCode)
        ON tlkpMasonryTyp.MasonryTypCode = tblMasonry.MasonryTypCode)
        LEFT JOIN (trelMUFe
            LEFT JOIN (tlkpFeTyp RIGHT JOIN tblFeature ON tlkpFeTyp.FeTypCode = tblFeature.FeTypCode)
            ON (trelMUFe.Site = tblFeature.Site)
            AND (trelMUFe.SUNum = tblFeature.SUNum)
            AND (trelMUFe.FeNum = tblFeature.FeNum))
            ON (tblMasonry.MUNum = trelMUFe.MUNum)
            AND (tblMasonry.Site = trelMUFe.Site))
            LEFT JOIN trelMUSU ON (tblMasonry.MUNum = trelMUSU.MUNum) AND (tblMasonry.Site = trelMUSU.Site)
WHERE (((tblMasonry.Site)='1825') AND ((trelMUSU.SUNum)='7-n'))
ORDER BY tblMasonry.MUNum

I know there is a bunch of stuff here but it seems to be stuck here:

tlkpCardinalDirection_1.Dir AS CornerAbutTo1,
tlkpCardinalDirection_2.Dir AS CornerAbutTo2,
tlkpCardinalDirection_3.Dir AS CornerAbutBy1,
tlkpCardinalDirection_4.Dir AS CornerAbutBy2,
tlkpCardinalDirection_5.Dir AS CornerTiedTo1,
tlkpCardinalDirection_6.Dir AS CornerTiedTo2,

Is the way the table and columns are represented here correct? Can you call the same table and just add an underscore with a number as make it an alias?

Thanks!

Answer 1

Thanks to Selvin for setting me on the right track. I got rid of the alias's and I changed this:

CASE
WHEN CornerAbutTo1 AND CornerAbutTo2 IS NULL THEN 'no data'
WHEN CornerAbutTo1 IS NOT NULL AND CornerAbutTo2 IS NULL THEN CornerAbutTo1
ELSE CONCAT( CornerAbutTo1, ' ', 'and', ' ', CornerAbutTo2)
END AS CornersAbutTo,

to:

CASE
WHEN tlkpCardinalDirection_1.Dir AND tlkpCardinalDirection_2.Dir IS NULL THEN 'no data'
WHEN tlkpCardinalDirection_1.Dir IS NOT NULL AND tlkpCardinalDirection_2.Dir IS NULL THEN tlkpCardinalDirection_1.Dir
ELSE CONCAT( tlkpCardinalDirection_1.Dir, ' ', 'and', ' ', tlkpCardinalDirection_2.Dir)
END AS CornersAbutTo,

That worked. Thanks!