Term
| What is the format for an INSERT command? |
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Definition
INSERT INTO [(columname,...)]
VALUES (datavalue, ...); |
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Term
| When can column headings be omitted in an INSERT commmand? |
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Definition
| If the data entered in the VALUES clause are in the same order as the comumns in the table. |
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Term
| When must you include the column names from an INSERT INTO commmand? |
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Definition
| If youu only enter data for some of the columns, or if the columns are listed in a different order than they are listed in the table. |
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Term
| How must a number that is defined as 'non-numeric' be inserted into a column? |
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Definition
| It must be encosed in a single quotation marks if the column's datatype is not NUMBER! |
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Term
| What error report is given if non-numeric columns are not enclosed in single quotation marks? |
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Definition
| qoted string not properly terminated. |
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Term
| What three approaches can be taken to enter NULL values when a row is added to a table? |
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Definition
1. List all the columns except the missing colun in the INSERT INTO cluase, and provide the data for the listed columns in the VALUES clause.
2. In the VALUES clause, insert two single quotation marks. Oracle9i will interpret the quotation marks to mean that a NULL value should be stored in the column.
3. In the VALUES clause, include the keyword NULL in the position. |
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Term
| When inserting a NULL value, what will Oracle9i interpret it to mean if NULL is enclosed in single quotation marks? |
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Definition
| It will try to store the word NULL in the column. (As a literal value) |
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Term
| What is the syntax for combining an INSERT INTO command with a subquery? |
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Definition
INSERT INTO tablename [(columname, ...)]
subquery; |
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Term
| What is the main difference between inserting data into using the INSERT INTO command with actual data and a wubquery? |
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Definition
| The VALUES clause is not included when the commmand is used with a subquery. |
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Term
| Does the INSERT INTO command require the subquery to be enclosed within a set of parenthes? |
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Definition
| NO. Although including the parentheses will not generate an error. |
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Term
| What is the syntax for an UPDATE commmand? |
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Definition
UPDATE tablename
SET columname = new_datavalue
[WHERE condition); |
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Term
| what does the SET clause identify? |
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Definition
| The column to be changed and the new value to be assigned to that column. |
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Term
| What does the optional WHERE clause in an UPDATE command identify? |
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Definition
| The exact row to be changed by the UPDAE command. |
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Term
| What happens if the WHERE clause is omitted from the the UPDATE command? |
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Definition
| The column specified in the SET clause will be updated for all records contained in the table. |
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Term
| What SQL command instructs Oracle9i to use a substituted value in place of the variable at the time the command is actually executed? |
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Definition
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Term
| What must be entered to include a substitution variable in a SQL commmand? |
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Definition
| Enter an ampersaned(&) followed by the name to be used for the variable in the necessaryl location. |
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Term
| Can usere view any changes you have made if you have not permanenty saved the table/ |
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Definition
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Term
| What is an explicit commit |
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Definition
| occurs when the command is explicitly issued by entering COMMIT. |
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Term
| What is an implicit COMMIT? |
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Definition
| Why the user exits the system by issuing the EXIT command. It also occus if a DDL command, such as CREATE or ALTER TABLE is issued. |
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Term
| When can a ROLLBACK command be used? |
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Definition
| When a COMMIT has not occured either explicity or implicitly. |
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Term
| What type of commands can use the ROLLBACK with? |
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Definition
| DML commands.. Comands such as CREATE TABLE, TRUNCATE TABLE, and ALTER TABLE cannot be rolled back baecause they are DDL commands and a COMMIT occurs automaticaly when they are executed. |
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Term
| What is the syntax for a DELETE ROW? |
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Definition
DELETE FROM tablename
[WHERE condition]; |
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Term
| Why does the DELETE command not allow the user to specify any column names? |
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Definition
| Because DELETE applies to an entire row and cannot be appied to spsecific columns with a row. |
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Term
| If youu omit the WHERE clause in a DELETE statement what will happen? |
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Definition
| All rows will be deleted from the specified table. |
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Term
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Definition
| When DML commands are issued, Oracle9i implicityl "locks" the row or rows being affect so no other user can change the same row(s). |
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Term
| What does the term 'shared lock' mean? |
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Definition
| Other users can still view the data stored in the table, but it prevents anyone from altering the structure of the table or performaing other types of DDL operations. |
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Term
| Locks will be automatically released under which conditions? |
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Definition
| If the user issues a trasaction control statement, such as ROLLBACK or COMMIT, or if the user exits the system. |
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Term
| What is the syntax for a SELECT....FOR UPDATE? |
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Definition
SELECT columnname,...
FROM tablename,
[WHERE condition]
FOR UDPDATE; |
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