In every code and sql editor, you can search for occurrences in the text and/or replace them.
Simply pressing Ctrl+F or using Search | Find brings you to the Find Text dialog (an example of this dialog is shown below).
The Find Text dialog
Using Ctrl+H or Search | Replace will bring up the "Replace Text" dialog, somewhat similar to the above dialog. Below is an example of this dialog.
The Replace Text dialog
Both dialogs can be used to find text, the latter has the added feature to being able to replace the found text. The hotkey F3 can be used to continue searching for a piece of text