This is personal study note
Copyright and original reference:
https://www.youtube.com/watch?v=SLaQHVZXDiE&list=PLVsNizTWUw7HhYtI-4GGmlJ5yxNdwNI_X
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Character set for client and server: UTF-8
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CAST(string AS time_type): convert string into time_type
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Variable
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Cast == Convert except syntax
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cast, convert: explicit convert
implicit convert (automatic convert)