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Test

Sin título

CJ Correll 12 preguntas

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Preguntas del test (12)

  1. 1In a join, column names need to be qualified only:
    1. Ain inner joins
    2. Bin outer joins
    3. Cwhen the code is confusing
    4. Dwhen the same names are used in both tables
  2. 2If you assign a correlation name to one table in a join,
    1. Ayou have to assign them to all of the tables
    2. Byou have to use that name for the table
    3. Cyou have to qualify every column name in the query
    4. Dyou have to qualify all of the column names for that table
  3. 3When you need to code multiple conditions in a join, its best to:
    1. Acode all conditions in the ON clause
    2. Bcode only join conditions in the ON clause
    3. Ccode all conditions in the WHERE clause
    4. Dcode only join conditions in the WHERE clause
  4. 4You don’t ever need to code a right outer join because:
    1. Aleft outer joins are just as efficient
    2. Bleft outer joins are easier to code
    3. Cright outer joins are less efficient
    4. Dright outer joins can be converted to left outer joins
  5. 5Which of the following is not a reason for using the explicit syntax instead of the implicit syntax for joins? The explicit syntax:
    1. Ais easier to read and understand
    2. Blets you separate the join and search conditions
    3. Ccan be used for more than two tables
    4. Dlets you combine inner and outer joins
  6. 6In a cross join, all of the rows in the first table are joined with all of the:
    1. Adistinct rows in the second table
    2. Bmatched rows in the second table
    3. Cunmatched rows in the second table
    4. Drows in the second table
  7. 7When you code a union that combines two result sets, which of the following is not true?
    1. AEach result set must have the same number of columns.
    2. BThe result sets may or may not have any duplicate rows.
    3. CThe corresponding columns in the result sets must have compatible data types.
    4. DThe result sets must be derived from different tables.
  8. 8When you code a union with the INTERSECT keyword to combine two result sets, the union:
    1. Aincludes only rows that occur in both result sets
    2. Bexcludes rows from the first result set if they also occur in the second result set
    3. Cincludes all rows that occur in both result sets if the primary keys are the same
    4. Dexcludes rows from the second result set if they also occur in the first result set
  9. 9A full outer join includes rows that satisfy the join condition, plus:
    1. Arows in the left table that don’t satisfy the join condition
    2. Brows in both tables that don’t satisfy the join condition
    3. Crows in the right table that don’t satisfy the join condition
    4. Dthe Cartesian product of the two tables
  10. 10SELECT VendorName, InvoiceNumber
    FROM Invoices LEFT JOIN Vendors
    ON
    Invoices.VendorID = Vendors.VendorID

    The total number of rows returned by this query must equal:
    1. Athe number of rows in the Invoices table
    2. Bthe number of rows in the Vendors table
    3. Cthe number of rows in the Invoices table plus the number of rows in the Vendors table
    4. Dnone of the above

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Test sobre Sin título, creado por CJ Correll el 08/11/2019.
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