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That would depend on your server settings. stripslashes() may be needed. But that only brings the data back to a central level. After that you need to add validation and verification specific to each piece of data.
Many databases have specific escapement requirements, so it's hard to say, but I guess I can assume you're using MySQL. In which case, you already have the function name above. However that only makes it potentially injection safe. However it does not protect you from using unexpected data in your queries. That is what validation and verification is for. What that specifically means varies on what you're specific data you are dealing with. If you're expecing numbers, make sure it's a number and so forth.