Helioseismology is a powerful tool to probe the internal structure and dynamics of the Sun. However, it requires long uninterrupted datasets to extract the rotational splittings with the highest precision. Two types of facilities were developed. On the one hand, ground-based telescopes such as the Birmingham Solar Oscillation Network (BiSON) and the Global Oscillation Network Group (GONG). On the other hand, the space-based instruments such as Global Oscillations at Low Frequency (GOLF) and Solar Oscillation Imager/Michelson Doppler Imager (SOI/MDI) on board the Solar and Heliospheric Observatory (SoHO), and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). In this work, we present the different datasets obtained, the methods used to extract the rotational splittings, and we study how to create a combined dataset of low- and medium-degree modes for inferring the solar rotation from the core to the surface.