Tagged Sub-optimal code (TSC) is a new coding technique presented in this paper to speed up string matching over compressed databases on PDAs. TSC is a variable-length sub-optimal code that supports minimal prefix property. It always determines its codeword boundary without traversing a tree or lookup table. TSC technique may be beneficial in many types of applications: speeding up string matching over compressed text, speeding decoding process, as well as any general-purpose integer representation code. Experimental results show that TSC is 8.9 times faster than string matching over compressed text using Huffman encoding, and 3 times faster in the decoding process. On the other hand, the compression ratio of TSC is 6% less than that of Huffman encoding. Additionally, TSC is 14 times faster than Byte Pair Encoding (BPE) compression process, and achieves better performance than searching over compressed text using BPE scheme on handheld devices.