4/30/2023 0 Comments Oracle sql developer nvl![]() You can use the REGEXP_REPLACE function, with regular expressions in the search pattern (the stored format) and references to those regular expressions in the replace string (the display format), as in Example 4-10. nnnn with their equivalents in the format ( nnn ) nnn-nnnn. Suppose that, in the displayed query results, you want to replace phone numbers that are stored in the format nnn. Result is similar to: FIRST_NAME LAST_NAME The third function parameter, 'i', specifies that the match is case-insensitive.Įxample 4-9 Selecting All Employees Whose Last Names Have Double Vowels SELECT FIRST_NAME, LAST_NAME The metacharacter \1 represents the first (and in this case, only) regular expression. The regular expression () represents any vowel. ![]() Suppose that you want to select every employee whose last name has a double vowel (two adjacent occurrences of the same vowel). Result is similar to: FIRST_NAME LAST_NAME JOB_ID The Results pane appears, showing the results of the query, which are similar to: FIRST_NAME LAST_NAME DEPARTMENT_IDĮxample 4-8 Selecting All Managers in the EMPLOYEES Table SELECT FIRST_NAME, LAST_NAME, JOB_ID In the field under "Enter SQL Statement:", enter this query: SELECT FIRST_NAME, LAST_NAME, DEPARTMENT_ID To select only FIRST_NAME, LAST_NAME, and DEPARTMENT_ID: This tutorial shows how to select only the columns FIRST_NAME, LAST_NAME, and DEPARTMENT_ID of the EMPLOYEES table. Tutorial: Selecting Specific Columns of a Table The query and its results disappear, and you can enter another SQL statement in the SQL Worksheet. The Results pane appears, showing the result of the query. In the SQL Worksheet pane, type a query (a SELECT statement). Under "Enter SQL Statement:" is a field where you can enter a SQL statement. If the Connection field does not have the value hr_conn, select that value from the drop-down list. Oracle has left open the possibility that the VARCHAR data type would change in a future release to adhere to the SQL standard (which is why everyone uses VARCHAR2 in Oracle since that data type's behavior is guaranteed to remain the same going forward).This topic explains how to run queries or other SQL statements in SQL Developer, if you are connected to Oracle Database as user HR from SQL Developer (for instructions, see "Connecting to Oracle Database as User HR from SQL Developer").Įither the Connection Information window opens or the SQL Worksheet pane appears. ![]() ![]() Violating the SQL standard (IMHO) was the least disruptive of these three options. So Oracle was basically left with the options of breaking existing code, violating the SQL standard, or introducing some sort of initialization parameter that would change the functionality of potentially large number of queries. By the time that the SQL standard came around and agreed that NULL and the empty string were distinct entities, there were already Oracle users that had code that assumed the two were equivalent. all of which constitute some sense of NULL). One should NEVER treat "BLANK" and NULL as the same.īack in the olden days before there was a SQL standard, Oracle made the design decision that empty strings in VARCHAR/ VARCHAR2 columns were NULL and that there was only one sense of NULL (there are relational theorists that would differentiate between data that has never been prompted for, data where the answer exists but is not known by the user, data where there is no answer, etc. ![]()
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