Glsl fragment - if else statements

Absolute beginner question here as you can guess. I'm trying to implement the most basic if else statement in my fragment shader, I have no error message but the first value of my vec4 color vector isn't changing at all.

#ifdef GL_ES 
precision mediump float;
#endif

uniform float u_time;
uniform vec2 u_resolution;
uniform float u_col1;

void main() {
    

    if ( u_time >= 0.1 )
    {
        float u_col1 = 0.1;
    } else {
        float u_col1 = 1.;
    }

gl_FragColor = vec4(u_col1,0.0,0.0,1.0);

}

You must declare a local variable before the if-else-statement and change that variable in the if-else-statement (this works like in most other programming languages):

#ifdef GL_ES 
precision mediump float;
#endif

uniform float u_time;
uniform vec2 u_resolution;

void main() {
    
    float u_col1;
    if ( u_time >= 0.1 ) {
        u_col1 = 0.1;
    } else {
        u_col1 = 1.;
    }
    gl_FragColor = vec4(u_col1,0.0,0.0,1.0);
}