Why is there a performance difference between two similar queries where one uses union and the other uses union all?

1032

---

What is a derived table?

928

---

Your sql server is running out of disk space. You notice that there are several large files with ldf extensions what are these files?

1189

---

Will the writetext statement activate a trigger?

1093

---

Other than truncate statement, which other command can by-pass the trigger on the tables?

1134

---

Is it important for a database administrator to understand the operating system and file access?

993

---

What is the fastest way to permanently delete a 1 million row table named customers?

1255

---

How do you rebuild an identity column?

949

---

Define a cross join?

1024

---

Explain an incremental backup?

1001

---

How will you know when statistics on a table are obsolete?

1082

---

How you can find out if an index is useful to the optimizer?

939

---

You want to check the syntax of a complicated update sql statement without executing it. What command should you use?

986

---

What are statistics?

999

---

Can a unique index be created on a column, which contains null?

919

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